PUERTO RICAN cuisine began with the simple cooking of roots, leaves, birds and fish by the original Indian tribes: the gentle Arawaks and Tainos and the cannibalistic Caribes (after whom the Caribbean region is named). The turtles they caught, the batatas they dug up, the hot chili peppers they blended into their pots, are all still part of the native cuisine.

But over a span of 500 years, the cuisine changed to reflect many new influences, especially the influence of the Spanish conquistadors. They invented the adobo -- spice blends pounded in a mortar for rubbing on raw chicken and meats -- and the sofrito -- an aromatic frying mixture of red oil and vegetables.

Also influencing the cooking was the cuisine of African slaves and, after the slaves were freed, those from India who came to work the coffee and sugar plantation, bringing their curries and mangoes. When New Orleans became American after the Louisiana Purchase, many of the French settlers there moved to Puerto Rico. Finally came Americans, who taught Puerto Ricans how to make hamburgers, hot dogs and sandwiches. In between these crucial events, the pure beauty of the blue-green island attracted smaller waves of immigrants who added their own innovations to the cuisine.

That homegrown cuisine is what I sought one evening when Ellen Hawes, Brooklyn-born San Juan food writer and television interviewer, took me for a progressive dinner, with each course at a different small bistro in the suburban neighborhoods of San Juan. At the end, I asked her which dish she would choose as being most representative of a Puerto Rican main course. She chose asopao de pollo, a one-dish casserole of chicken buried in a spicy, vegetable-studded layer of rice. This famous dish -- universal in every Puerto Rican home, poor or rich -- involves cooking the rice so that it becomes slightly mashed and soft, rather than keeping the grains separate. Clearly, the dish has strong links to Italy's risotto and China's congee -- both dishes in which the rice is deliberately slightly mashed. PUERTO RICAN ASOPAO DE POLLO (Casserole of chicken with soft rice) (4 servings) Red oil: 1/4 cup whole achiote (annatto) seeds (available at Latin American or Mexican markets or spice shops)* 1/2 cup olive oil Adoba: 2 cloves garlic, sliced 1 teaspoon crumbled, dried oregano 1/2 teaspoon paprika, preferably Hungarian medium-hot 1 teaspoon red wine vinegar 2 teaspoons coarse sea salt or kosher salt 4 whole black peppercorns 3 1/2-pound chicken, cut into 8 pieces Sofrito: 1/2 cup boiled ham, coarsely diced 1/4 cup washed salt pork, finely diced 1 medium green pepper, coarsely diced 2 medium red peppers, coarsely diced 1 large yellow onion, chopped Chicken and rice: 1-pound can peeled Italian plum tomatoes 3 Spanish chorio or about 6 ounces Italian pepperoni sausages, cut into 1/2-inch slices 2 4-ounce cans sweet red pimento, contents of 1 can chopped with juice; second reserved for garnish 7 cups clear chicken bouillon 2 cups short-grain white rice 2 tablespoons drained capers 20 green olives 3/4 cup green peas Freshly ground black pepper 16 asparagus tips, cooked 1 cup freshly grated parmesan cheese 1/4 cup coarsely chopped fresh coriander leaves (cilantro), optional

To prepare the red oil, put seeds into small saucepan and add hot water to just cover. Boil gently 5 minutes. Remove from heat, cover, and let soak 2 hours.

Remove seeds with a slotted spoon (reserve red water) and put into a mortar. Coarsely crack seeds, then transfer to a food processor and add about 2 tablespoons of the red water. Process into a smooth puree. Return to the red water and boil hard to evaporate the excess water and concentrate the red color oils. Stir steadily until a stiff paste is formed. Over high temperature, work in olive oil smoothly. At first there will be heavy bubbling as the last of the water boils off. When the liquid becomes still, heat until there is a light haze over the surface of the oil and a slight smell of scorching. Do not let it burn. At once, remove saucepan from heat, cover, and let cool to room temperature, about 1 hour.

Strain off the bright red oil and store in a screw-top jar in the refrigerator. This is an excellent frying oil for chicken, fish, meats and sauces.

*Note: If you cannot get achiote seeds, you can do without the red oil and just use the olive oil. But you will lose the red that makes this dish so attractive, and also some of its Caribbean authenticity.

To prepare the abodo, put garlic, 2 teaspoons of red oil (or olive oil), oregano, paprika, vinegar, salt and black peppercorns into a mortar. Pound and grind into a paste. Rub thoroughly over chicken pieces; set aside on board to absorb flavors.

To prepare the sofrito, place a heavy iron casserole over medium-high frying heat and add 3 tablespoons red or olive oil. When the oil is hot, but nowhere near smoking, add ham and salt pork. Saute, stirring, until lightly browned, about 2 or 3 minutes. At once, stir in green and red peppers and onion. Cook, lightly stirring, until onion is soft but not browned, about 4 minutes.

Stop sauteeing by adding tomatoes with juice, sausage, chopped pimientos and juice, and 2 tablespoons of red or olive oil. Simmer gently, uncovered, for 5 minutes.

When sofrito is ready, place in it pieces of chicken (including giblets). Simmer gently, covered, until chicken is about 1/3 cooked, 7 to 12 minutes. Remove chicken and set aside.

Meanwhile, in a separate saucepan, heat chicken bouillon to boiling. Pour into casserole, bring to a gentle bubbling and stir in rice. Gently simmer, uncovered, until rice is tender and the whole dish has softly congealed. The usual time for the rice is 20 to 30 minutes. After the first 10 minutes, return chicken to pot, burying the pieces of the rice. About 15 minutes before the end of cooking, gently work capers, olives, peas, and a generous grinding of black pepper into the rice.

A classic asopao is not supposed to be as stiff as a paella, but is to be eaten with a spoon from a bowl or soup plate. It should be thick enough to mound in the spoon. You can adjust the thickness to your taste by controlling the cooking time and, if necessary, thinning it with a bit more liquid or thickening it by boiling it fairly hard for a few extra minutes. The longer it cooks, the thicker it gets.

While waiting for the rice to cook, lightly heat asparagus tips and the remaining red pimiento, cutting the latter into pretty shapes.

Just before serving, stir grated cheese and coriander leaves into chicken. Garnish each serving of asopao with the asparagus and red pimiento.