THERE ARE people who cook by touch--poking at the roast to see by its re- sistance whether it is rare, medium or well done; or nudging the chicken leg to see if it moves. There are people who cook by smell, and people who cook by sound--the crackle of the crust, the heavily plopping bubbles of a properly thickened tomato paste.

Then there is Prema Suppiah, who cooks by color. She knows whether her spice paste has developed sufficient flavor by how dark it has grown in the hot pan, and whether the balance of seasonings is correct by the hue of the finished sauce. And she'd better, because as a vegetarian she refuses to even taste her own chicken korma or pork vindaloo.

But her restraint doesn't stop there. Even her vegetarian dishes are concocted by eye rather than by palate, since Suppiah's repertoire is Southeast Asian but she doesn't like chilies. Chef for Kishore Mahbubani, deputy chief of mission at the Singapore Embassy, Suppiah serves a buffet of nine main dishes ranging from South Indian Pork Vindaloo to Indonesian Sayor Lodeh to Nonya Shrimp Sambal to her own original Eggplant Patchree. And she sits down herself to salad and crackers.

As Mahbubani says, "Prema's mission in life is to feed others."

She does that in Mahbubani's home, in friends' homes and sometimes in New York, as when Mahbubani recently took her there to cook four days' worth of official dinners during the U.N. General Assembly. She has even cooked her Ceylonese Chicken for Nora's restaurant and taught owner Nora Pouillon how to make the Indian breads that now appear on the restaurant's menu. "She opened to me the new horizon of Indian breads; she took the scare out of it," Pouillon said of Suppiah's bread lessons. She also tried to sell Pouillon her cheesecake.

For Prema Suppiah is more than an Indian chef turning out Singapore cuisine. Having grown up in Malaysia with a taste for travel, she has investigated the kitchens and cooking techniques of England, Nepal, Japan and Singapore, considers shepherd's pie and hamburgers as much her specialties as pakoras and chow mein.

Most notably, though, for the last year and a half in Washington she has spread the taste for Singapore's cooking among friends and acquaintances as she cooked for them officially and unofficially. One friend insists that Suppiah can't keep her hands off food; she will come by for a social visit and automatically start something marinating or simmering in the friend's kitchen. And on the diplomatic circuit, said one "deep background" source, "Her cooking has really improved Singapore's stature." The embassy was never known for its entertaining until Suppiah arrived, continued the source; her cooking has put the Singapore Embassy in people's minds and on their lists.

Once settled in Washington, Suppiah learned the fine culinary art of making do. She grows mint in the back yard now, and avoids using msg by boiling down bones "for hours and hours" to develop flavorsome broths that don't need an enhancer. She has learned to cook on a typical American electric stove.

There are also compromises. As a visual cook, she seeks a bright yellow for her rice, studded with dark brown shreds of onion ("the proper browning of onions is the most important part of cooking," she explains); bright red for her sauce of chilies; a bright melange of colors from grated cucumbers, tomatoes and parsley in her yogurt; and she uses food coloring in some dishes to intensify what might have been more naturally vivid hues at home.

One substitute she will not make is in her cookware. "Whenever I travel these go first in my suitcase," says Suppiah of her two iron woks, both from Nepal and more than 30 years old, one a heavy dark iron and the other shiny inside and encrusted outside with a golden glaze.

And while she is teaching her Washington circle about the colors and tastes of Southeast Asia she is watching with equal care what goes on in Western kitchens. Suppiah is studying hotel management, and spins colorful thoughts of running a small hotel with a restaurant serving "all kinds of food." But that's a long way off from her first exams, and clearly in the dreaming stage: "We'll call it The World Cuisine. Does that sound nice?"

Here are Prema Suppiah's recipes for some of the dishes she serves to the Embassy of Singapore's official and unofficial guests but hasn't tasted herself. We have, though, and we vouch for them. CHICKEN KORMA (10 servings) 3/4 cup blanched almonds 2 large onions 2-inch piece ginger 6 cloves garlic 3 tablespoons coriander seeds 1 1/2 tablespoons cumin seeds 2 1/2 tablespoons anise seeds 1 tablespoon white peppercorns 1 tablespoon poppy seeds 5 dried red chilies, seeded 1/2 teaspoon turmeric powder 1 large tomato 10 pounds whole chickens or 5 pounds breast meat 1 tablespoon flour 2 tablespoons salt 1/4 cup oil 2-inch stick cinnamon 5 cloves 3 whole cardamoms or 1/2 teaspoon ground Juice of 2 limes 1/4 cup yogurt 1/4 cup mint leaves Salt to taste 1/4 cup chopped coriander leaves

Put almonds in a blender with 1/4 cup of water and grind until fine. Blend onions separately and blend ginger and garlic together. Set aside. Put a frying pan over medium heat. Fry coriander seeds, cumin seeds, anise seeds, peppercorns, poppy seeds, dried chilies and tumeric powder together in a skillet for 10 minutes, stirring to keep them from burning, and cool. Use a coffee grinder and grind fine. Meanwhile dice tomato and cut chicken. If you are using chicken breasts, halve each. If you are using whole chickens, cut each into about 8 pieces. Throw away as much fat as you can from chicken. Combine flour and salt and rub into chicken. Let it stand for 5 minutes. Wash chicken under running tap water and strain it in a colander and dry with a paper towel. Heat a large pan over high heat. Add oil, cinnamon, cloves and cardamoms. Fry for 5 minutes. Add pure'ed onions. Fry for 5 or 10 minutes, stirring occasionally, until onions are browned. Add pure'ed ginger and garlic, stir and fry 7 minutes, and add all the ground spices and stir them continuously until they release their flavor and aroma. Add tomato, cover pan and cook about 10 minutes over medium heat. Gradually stir in the ground almonds. If mixture is too dry, add 1/4 cup of water and let it simmer for 10 minutes. Now, turn heat back to high and add chicken. Add lime juice, yogurt (make sure there are no lumps in yogurt), mint leaves and salt to taste, and cook for 20 covered minutes, stirring often and adjusting heat so it doesn't burn. If chicken is cooked and the gravy is still watery, remove from the gravy. Let gravy simmer until it thickens, then return chicken and remove from heat. Add coriander leaves and serve. PORK VINDALOO (8 servings) 8 dried red chilies, halved and seeds removed 1 tablespoon cumin seed 1 tablespoon mustard seeds 1 teaspoon of tumeric powder 8 cloves garlic 1 large onion 1 inch fresh ginger, sliced 3 tablespoons oil 3/4 cup tomato pure'e 1/4 cup white vinegar 2 tablespoons sugar 1/2 teaspoon salt or to taste 3 pounds lean pork tenderloin (cut in thumb-sized pieces) 2 tablespoons chopped coriander leaves Rice for serving

Soak chilies, cumin seeds and mustard seeds in hot water for 1 1/2 hours or longer. Drain and combine with turmeric, garlic, onion, ginger in a blender. Add about 1/4 cup water and blend them fine. Heat a large pan and pour in oil. Fry all the blended ingredients until mixture thickens and oil begins to separate from the mixture. Add tomato pure'e. Cook, stirring, for 3 minutes. Add vinegar and sugar and bring to a boil. Add salt to taste and pork. Bring to a boil over high heat and cook 5 minutes, stirring constantly. Reduce heat and simmer for about 20 minutes, occasionally stirring, until pork is cooked through and vindaloo is dry. Add coriander leaves and remove from heat. Serve over rice.

This dish can be cooked a day ahead and refrigerated. EGGPLANT PATCHREE (6 servings) 1/4 teaspoon anise seed 4 dried chilies 5 shallots 1 inch ginger root 2 cloves garlic 1/2 teaspoon cinnamon 1/4 cup tomato pure'e 1 tablespoon coriander powder 1 1/2 tablespoons cumin powder 1/4 teaspoon turmeric 2 eggplants, peeled and cubed 5 tablespoons oil 1/3 cup tamarind or dates 1/3 cup sugar 1/2 teaspoon salt or to taste

Cover anise seeds, chilies, shallots, ginger root and garlic with boiling water and soak 1 1/2 hours. Drain water and put ingredients in blender. Add 1/4 cup water, cinnamon, tomato pure'e, coriander, cumin and turmeric. Blend. Soak eggplants in water with 1/4 teaspoon salt. Drain and dry. Fry in 3 tablespoons oil until lightly brown. Drain. Add 3/4 cup water to tamarind. Soak 20 minutes. Squeeze tamarinds and extract juice. Discard tamarind. Add 2 tablespoons oil to wok or pan and fry mixture of spices until oil is floating. Add sugar, salt and tamarind juice. Cook until tamarind juice dries. Add eggplant and cook 15 minutes. Reheats well. FRIED BEE HOON (Chow Mein) (4 to 6 servings) 1/2 to 3/4 pound Chinese rice vermicelli (bee hoon) 1/4 cup dark soy sauce 1/4 cup oil 6 cloves garlic, chopped 1 large onion, chopped 1 pound chicken, julienned 1 cup fresh mushrooms, sliced 2 eggs, lightly beaten 2 teaspoons pepper Salt to taste 1/2 cup scallions, chopped 1 pound bean sprouts 1/4 cup water Carrot or red chilies for garnish For garnish: onion rings saute'ed until very browned

Soak bee hoon in cold water for 3 hours. Drain and mix with soy sauce and set aside. Heat wok or frying pan. Add oil, fry garlic and onion until golden brown. Add chicken and keep frying, until chicken is cooked. Add mushrooms, keep frying for 5 minutes. Add eggs, pepper, salt. Fry for 3 minutes. Add bee hoon, scallions and bean sprouts. Fry for 15 minutes, stirring all the time and sprinkling water to prevent bee hoon from burning. Garnish with carrot or red chilies and browned onion rings. MUTTON MYSORE (2 servings) 1 1/2 pound lean lamb 4 cloves garlic 1 tablespoon chopped mint or coriander Salt to taste 1 1/2 tablespoons chili powder 1 tablespoon cumin powder 3/4 teaspoon turmeric powder 1 teaspoon white vinegar 1 teaspoon sugar 1 tablespoon light soy sauce 2 tablespoons butter

Rice or french bread for serving

Cut the meat into pieces about 1/2-inch thick. Wash and dry them. Set aside. In a blender pure'e garlic, chopped mint and salt. Combine blended mixture with spices, vinegar, sugar and soy sauce. Rub well into the meat and let it stand for 2 hours. Heat butter in a heavy pan and add meat. Do not add any water. Cover the pan and cook on low heat, stirring from time to time until the meat is tender, about 10 to 15 minutes. Remove the lid to allow any moisture to evaporate and continue cooking until the meat fries to a rich brown color.

Serve with rice or french bread. FRESH MINT CHUTNEY (Makes about 1 cup) 1 1/2 cups fresh mint leaves 4 shallots 3 fresh green chilies Salt to taste 1 1/2 teaspoons sugar 2-3 tablespoons vinegar

Put mint leaves in the blender with shallots and chilies and blend until fine. Then add sugar, salt, vinegar. Blend for 4 minutes until well-mixed. Store covered in the refrigerator until needed. Serve as an accompaniment to meat dishes or curries.