NO LONGER ARE just hamburgers, hot dogs and chicken smeared with barbecue sauce being grilled in America's back yards. Shark, lightly curried boneless chicken and steak with green peppercorns and cre me frai che are just a few novelties that go well on the grill.

For the fastest cooking as well as the most convenient presentation, do them as kabobs--efficient to marinate, handy to portion, pretty to serve.

According to Moe Cheramie, of Old New Orleans Seafood in McLean, Mako shark is the kind to buy. It's delicately flavored, unlike some West Coast shark; and at half the cost, has the rich, smooth texture of swordfish. Marinate shark in a mayonnaise-based sauce to keep it moist. Bamboo skewers should be soaked in water for half an hour before using to inhibit burning on the grill.

Curry marinade improves with age. Combine it with vegetables such as squash, peppers, cherry tomatoes and mushrooms for a curried vegetable kabob. Vegetables need to be marinated for only an hour. Thread two pieces of curried chicken separated by a red pepper square onto a four-inch bamboo skewer and serve as an hors d'oeuvre. Use either all light meat or all dark meat for individual kabobs, since dark chicken pieces such as thighs will need an additional 3 to 4 minutes on the grill. The mushrooms soak up the curry flavor of the marinade. Look for clean white mushrooms that need only a light wipe. Do not wash, or the mushrooms will absorb water and become soggy.

Marinate beef, salmon, flounder or swordfish in cre me frai che and green peppercorns. This marinade can double as a sauce if the peppercorns are reduced by one-half tablespoon. Season with tarragon, if desired. Do not marinate vegetables in the cre me frai che, as their color is obscured.

Cooking times for barbecued food vary with the type of barbecue and fire, the intensity of the fire, the distance of food being barbecued from the fire and the density of the food. Experience is the key to determining when the food is done.

Heat can be regulated by how the grill's cover is placed. A covered fire or a partially hooded one will be hotter than an uncovered fire.-

Dense foods, such as roasts and food with bones, require longer cooking. Sear meats first on both sides over high heat to seal juices in, then lower heat for the remaining cooking time. Less dense foods with high water content, such as zucchini or cherry tomatoes, will cook quickly, as will small pieces of food for kabobs. Since the cooking time is short, high heat may be used with little danger of toughening the food.

Test meats or fish for doneness by pressing with a finger. The longer they cook, the firmer the food becomes. Thus, raw meat or fish will be very soft, and pressing firmly will almost leave an indentation. Rare food will resist the pressing slightly. The outside will be cooked and the inside will not be. Medium-done meat should be firm, but still springy to the touch. The pressing test method works for poultry as well. Use a meat thermometer for pork. The cooking times for these kabobs were tested on a gas barbecue on high heat. Adjust times according to your individual situation. CREOLE-STYLE SHARK KABOBS (4 servings) 1 1/2 pounds fresh shark steaks, 3/4-inch thick (swordfish may be substituted) 1 small white onion, peeled and quartered 8 cooked okra (frozen, thawed okra may be used), or 1 small green pepper, seeded and cubed 8 9-inch bamboo or metal skewers Shark marinade: 1/2 cup mayonnaise 1 teaspoon fresh lemon juice 1/2 teaspoon creole mustard 2 scallions, green and white parts, minced 5 to 6 dashes hot pepper sauce Freshly ground black pepper Pinch cayenne (optional) Vegetable marinade: 3 tablespoons olive oil 1 1/2 teaspoons fresh lemon juice Freshly ground black pepper

Remove skin from shark steaks. Cut steaks into 32 3/4-inch squares. Set aside. Separate onion segments. Cut okra into 3/4-inch long pieces, removing stem end (24 pieces).

In a medium-sized bowl, mix the mayonnaise, lemon juice, mustard, scallion, hot sauce, pepper and cayenne. Taste and adjust seasonings. The marinade should be spicy. Add the shark pieces and toss to coat well. Refrigerate, covered, for three hours. Mix the olive oil, lemon juice and pepper. Add the okra and onion and marinate three hours.

Alternate the shark, okra and onion on the skewers. Pre-heat grill and brush cooking surface lightly with oil to prevent sticking. Broil 4 to 6 minutes total, turning kabobs every 2 minutes. Serve hot with parsleyed new potatoes and fresh asparagus or green beans. Stuffed tomatoes are also a nice accompaniment. Pass lemon wedges with the shark. CURRIED CHICKEN KABOBS (4 servings) Marinade: 10 tablespoons peanut oil 1 small white onion, peeled and finely chopped 2 garlic cloves, peeled and minced 1/2 teaspoon minced fresh ginger 1/2 teaspoon turmeric 1/2 teaspoon chili powder 1 teaspoon cumin 1/4 teaspoon each salt, black pepper and dry mustard 1 1/2 teaspoons tomato paste 1 tablespoon fresh lemon juice For the kabobs: 4 half chicken breasts, skinned and boned 32 medium mushrooms 1 medium red onion, peeled and quartered 8 9-inch metal or bamboo skewers

Make marinade two days before using. In a heavy skillet heat 2 tablespoons peanut oil on low heat and saute' onion for 5 minutes until translucent and soft. Do not brown. Add garlic, ginger, turmeric, chili powder, cumin, salt, pepper and mustard. Stir to mix, and saute' for 4 minutes. Whisk in tomato paste, lemon juice and 1/2 cup peanut oil. Heat for 1 minute. Cool, cover and refrigerate.

Separate small fillet from back of chicken breast. Cut each half breast and fillet into 10- to 12 3/4-inch cubes. Wipe mushrooms with a damp paper towel and trim stem end. Add chicken to marinade and marinate for 4 hours. Add mushrooms, toss to coat, and marinate 1 hour. Alternate 5 to 6 pieces of chicken per skewer with 4 mushroom and onion segments.

Preheat grill. Brush cooking surface lightly with oil. Grill chicken for 6 to 8 minutes total, turning every 2 minutes. Serve hot with steamed rice and stir-fried snow peas. BEEF EN BROCHETTE (4 servings) 2 pounds sirloin steak, 3/4- to 1-inch thick 16 medium-sized mushrooms 1 green pepper, seeded 1 medium-sized red onion, peeled and quartered 16 cherry tomatoes 1/4 cup olive oil Marinade: 1 1/2 tablespoons green peppercorns, drained 1/2 teaspoon salt 3/4 cup cre me fraiche 2 tablespoons white wine vinegar 2 tablespoons chopped parsley 8 9-inch metal or bamboo skewers

Trim fat from steak and cut meat into 32 1-inch cubes. Set aside in a medium-sized bowl. Wipe mushrooms and trim stems. Cut green pepper into 16 1- inch chunks. Wash cherry tomatoes. Leave stem end on.

In a mortar or small bowl, mash the green peppercorns with the salt until a paste is formed. Gradually mix in the cre me frai che. Stir in the white wine vinegar and parsley. Add cre me frai che mixture to meat and toss to coat. Marinate for 4 hours or overnight, covered and refrigerated.

Just before skewering, toss mushrooms, onions and cherry tomatoes with the olive oil. Alternate the meat with the vegetables on the skewers. Pre-heat the grill. Brush cooking surface lightly with oil. Grill meat 6 to 8 minutes total, turning every 2 minutes. Serve with herbed pasta, cucumbers vinaigrette and miniature finger rolls.