IN ALASKA, a vendor toasts bagels on an open grill, offering cream cheese and other condiments from open compartments on the side of the pushcart. Trucks line downtown streets in Trinidad, the vendors skewering and grilling curried meats within. Frusen Gladje, the latest "designer ice cream" to bombard New York, is being scooped into cones and cups on 42nd and Madison.

Never in Washington. Health regulations say no.

The Alaskan vendor wouldn't last one hour in downtown D.C. because: a) the toasting device would have to be located inside the cart and the bagels would have to be stored in an enclosed area, and, b) the cream cheese would have to be prepackaged and maintained at 45 degrees or below. As for the trucks in Trinidad, it's strictly prohibited here to clean, cut, process or prepare fish, poultry or animals in a food vending vehicle (hot dogs don't count since they're already processed). And forget about seeing hand-dipped ice cream in Washington. According to supervisor-sanitarian Grover Tate, "You can't control the growth of bacteria on the dippers."

Sgt. Mitchell C. Dudley, the District police's vending coordinator, admits that food vendors have limited capabilities. "Health regulations make it very strict. Their equipment will not allow them to get too exotic."

A local Vietnamese vendor wanted to make his country's specialties on board his truck, but that would have meant refrigerators to store fresh produce. Another vendor thought of making crepes, but dropped the idea when he realized what it would cost to install an enclosed griddle. And according to the health department, it has received inquiries regarding everything from enchiladas and tacos to soups, spareribs and fresh fruit sundaes.

It's not that they can't be done, says John Grisby, supervisor sanitarian at the District's health department. "But the big thing is getting the equipment." Constructing equipment to comply with health department specifications is a costly endeavor, especially, said Grigsby, "if you don't know whether it's going to catch on or not." And, according to Grigsby, national manufacturers build separate carts for the District from those for other cities. Corner Gourmet's carts, which were built expressly for that company, cost approximately $3,000 each.

The rules and regulations are complicated, depending on what a food vendor has planned, especially if he intends not to prepackage the item. For example, requirements for Corner Gourmet's carts had to include:

* hot and cold running water

* a hand basin for the vendor to wash up

* a spillage sink

* a retention tank for waste water

* a trash receptacle

* cleanable surfaces

* covered food preparation area

* food handled from the inside, not outside

There are deterrents, though, in selling prepackaged goods. Maintaining freshness is difficult. Tate of the health department agrees. "Chinese food out of the wok and onto your plate is what you want. Quality breaks down when you prepackage it."

All vendor carts must be inspected before they can operate in the District. In addition, the commissary or depot where the foods are stored, shipped and prepared must be approved by the health department. That can never be in the vendor's home, unless he has an inspected kitchen which meets stringent requirements.

Any prepackaged product that crosses state lines must have ingredient and weight labeling. In addition, a company like Chipwich--whose product is shipped from New Jersey and is stored in Virginia--had to have written approval from both states' health departments before beginning operation in the District.

There are other kinds of regulations: where vendors can and cannot stand, how far apart they can be from each other, cart size specifications.

The reasons for all the rules? "To protect the public," says the health department's Grigsby. "Our greatest goal will be to make sure no one gets sick," says the police department's Dudley.

And so, exotic food possibilities aside, here is a review of the food on the streets so far this year (hot dogs, Good Humor and other usuals excluded). Remember, since vendors frequently change "offices," locations are hard to pinpoint. You'll have to case the streets yourself.

* Chipwich--Slicker packaging than Chips A La Mode, and not as messy to eat, although considerably smaller. Chips themselves were small; company says they are imported Dutch. A firm sweet cookie reminiscent of the ones sold in bulk in the supermarket. The ice cream--both chocolate and vanilla--lacked richness, with all the same weaknesses as ice milk. Chipwich eventually plans to sell imported Italian chocolates.

* Chips A La Mode--If Chipwich is the true machine-made sandwich, this is the genuine man-made. A big cookie, big chips and lots of creamy Carvel ice cream. The irregular-sized cookies (a homemade sign as opposed to the uniform Chipwich) were a bit gummy and soft, and had a tendency to stick to the ice cream and the fingers. Chips A La Mode come in vanilla, chocolate, mint chocolate chip, with guest flavors like jamoca almond fudge, coffee, butter pecan, peanut butter chip. Coffee was tops.

(Our tasters agreed that both chocolate chip ice cream sandwiches we tried deserved to be better. The cookie needs to be firm enough to support the ice cream and not too sweet; the ice cream need not be overly sweet either, but needs to be a creamy contrast to the cookie.)

* Briefcase Breakfasts--Collins herself says the muffins could be better. We tried the blueberry and agree. The banana nut (recipe below) are a big step up.

* Homespun's Jam Cakes--True to their name, these cakes are a homey spin-off on applesauce cake. The apple jelly flavor was barely discernible in our sample, but you can't go wrong with the orange marmalade (spiked with Triple Sec, see recipe below). Becker says the lemon marmalade is a winner, too.

* Sidewalk Cafe--This is a high-quality operation. Bagels, which come from the Georgetown Bagelry, are sold with butter, salmon spread, cream cheese or cream cheese and lox, with good amounts of each, too. (Vendor Paul Auld says he's having a hard time selling bagels with cream cheese; he gets a lot of requests for them with peanut butter and jelly.) There are also french bread sandwiches (bread from Vie de France) served with really rare and nicely lean roast beef, slathered with a top-notch, "top secret" mustard sauce that we figured is some combination of dijon, mayonnaise and maybe a little worcestershire. Polish ham and gouda cheese sandwich is not to be passed by, either.

* Corner Gourmet--Plain croissants: Not bad for a cart version, butter-laden, huge and semi-tough. And for those who can't leave well enough alone, there are filled croissants. Raspberry: The best of the filled, oozing with great-tasting seedy jam, sprinkled with powdered sugar--the grown-ups' jelly doughnut. Strawberry: We've had better canned pie fillings. Almond: For devotees of the nut only. Chocolate: Its bittersweet chocolate is not overpowering, but it's still hard to stomach a whole one. Cheesecake: Artificial tasting, but not as bad as anticipated. Ham and cheese: Just a little roll of disappointing ham, lightly lined with melted cheese. Pastrami: Meat is slightly better quality than ham, but can't they both stay where they belong--with rye bread?

* Old Fashioned Bakery--The red-checkered tablecloths and red cookie baskets are trademarks for this stand. The spice cake with cream was the best of the cake bunch. Cookies were average, but we decided the sun had soaked the oomph out of them. Oatmeal-nut-raisin cookies (recipe below) are new acquisitions; a lot of good stuff in one cookie.

* Le Sorbet--Prepackaged ices from the stores, with calorie counts for the conscious. The countdown per four ounce serving (the prepackaged cups on the truck are 3 1/2 ounces): Orange: 71. Cantaloupe: 72. Raspberry: 78. Strawberry: 86. Lemon: 96.

* The Nut Man--Rumor has it that he has been seen in the Connecticut Avenue corridor selling all kinds of exciting nuts, but repeated searches, both through the health department and by foot, failed to uncover him. Food To Come:

* Frusen Gladje--A Swedish-style ice cream of the high butterfat kind;the company is bringing several carts here at the end of June. Look forward to fruity sorbets in addition to some glitzy-sounding flavors like vanilla roasted almond and Swiss chocolate candy almond.

* Swensen's Gookies--As soon as ingredient labels are printed, these chocolate chip ice cream sandwiches will return to Corner Gourmet's carts. They'll also be selling Swensen's crunch cones (ice cream cones topped with diced almonds) and mock ice cream sundaes--dixie cups sold with prepackaged toppings (fruit and fudge).

Here are a few recipes off-the-street to make at home: FAITH COLLINS' BANANA NUT MUFFINS (Makes 12) 6 tablespoons butter, melted 1/2 cup sugar 1 egg, lightly beaten 1/2 teaspoon salt 1 teaspoon vanilla 1 1/2 cups all-purpose flour 1 teaspoon baking soda 1 teaspoon baking powder 1 cup mashed bananas 3/4 cup chopped walnuts

Combine butter with sugar, egg, salt and vanilla. Sift together flour, baking soda and powder. Add to butter mixture. Stir just until combined. Add mashed bananas and walnuts and put into greased muffin tins. Bake at 350 degrees for 17 minutes. HOMESPUN'S MARMALADE CAKE (Makes a 9-inch cake) 2 1/8 cups sifted cake flour 1/2 teaspoon baking soda 1/2 teaspoon baking powder 1 stick unsalted butter 3/4 to 1 cup sugar 2 eggs, separated 1 teaspoon Triple Sec or vanilla (optional) 8-ounce jar marmalade, either lemon or orange

All ingredients should be at room temperature. Sift flour, measure and resift with soda and baking powder. Cream the butter and sugar, using less sugar if the marmalade is sweet. Beat in egg yolks. Add flour mixture and marmalade alternately and a teaspoon of additional flavoring if desired. If the marmalade is stiff and if the batter isn't fluid, add a tablespoon of water. Beat the egg whites until stiff but not dry and fold gently into cake mixture. Pour into a well-greased 9-by-9-inch pan. Bake at 350 degrees for about 1 hour or until toothpick inserted comes out clean. Cake should be honey-colored. OLD FASHIONED BAKERY'S OATMEAL-NUT-RAISIN COOKIES (Makes about 4 dozen) 1 cup honey 1/2 cup oil 2 eggs, slightly beaten 1 teaspoon vanilla 2 teaspoons cinnamon 1/2 teaspoon salt 2 cups rolled oats 1 1/2 cups whole-wheat flour 2 teaspoons baking powder 1/2 cup pecans, chopped 1/2 cup almonds, chopped (or can substitute 1 cup walnuts for both pecans and almonds) 1 cup raisins

In a large mixing bowl, combine honey and oil. Add eggs. Mix. Stir in vanilla, salt and cinnamon. Add rolled oats, flour, baking powder, nuts and raisins. If mixture seems too dry, add a little milk to thin it out. If it is too sticky, add a little wheat germ to bind it. Drop batter by teaspoonfuls on a cookie sheet. Bake approximately 12 minutes in a 350-degree oven.

Variations: 1) Eliminate raisins and add 1 cup chopped dates. 2) Reduce flour to 3/4 cup and add 1 cup coconut shreds. 3) Toast oats before using them.