Open daily, 11 a.m. to 3 p.m. and 6 to 11 p.m. AE, BA, CB, MC. Reservations.

Prices: Dinner main dishes $5.50 to $9.50.

LAST time I had visited the site, it was a Middle Eastern restaurant. On my first visit to Costa del Sol, two restaurants on the block were fixing to reopen under new management. That's the scene on Arlington's restaurant strip. The French restaurant you visited last week may be Korean this week, and next week French again. However, a few hang on, and Costa del Sol looks as if it could be one of those.

The decor made an easy metamorphosis, its white stucco walls and brick-edged arches readily Spanish, the walls now etched with phrases from Don Quixote and cattle brands, hung with a couple of fringed shawls and the horse collar that seems to be required of every Northern Virginia restaurant, be it French or Texan. Even so, a pretty, spacious setting is hardly enough for long-term success.

The waiters could be enough.Costal del Sol has acquired a well-trained black-tie crew who combine dignity and friendliness in fine balance, who take the order with charm and deliver it with efficiency - and unfortunately, sometimes chew gum while they do all that.

Barring that feat of mental dexterity and visual irritation, the waiters do a good job - only slightly better than the kitchen.

To appreciate the kitchen, remember that even when served with black tie, Spanish food is far earthier stuff than French or Northern Italian. Sauces are heavy, seasonings are abundant, garlic is nearly a main course rather than a faint accent. To plunge into the genre, you could start with gambas al ajillo, shrimps in a tiny clay casserole, swimming in garlic, olive oil and parsley. Or garlic soup, a robust red broth weighted with slices of bread, salty couuntry ham, paprika-scented chorizo, a poached egg,, a light olive oil slick and even more garlic. The garlic theme - you will probably be addicted by now - comes through the frothy pink gazpacho, more delicate than most versions. The perfume hovers over the table. But the theme does not predominate every dish; conchitas - clam shells stuffed with carb, olives, capers and pimento - are a subtle appetizer. And fried squid tastes only of lemon and a crunch of flour coating.

In Spanish restaurants, one learns with experience that appetizers are often the stars. At Costa del Sol, as in many others, a meal of all appetizers would be ideal. But generally one goes on to main courses.

Whether or not it is a conscious touch, the menu is evenly balanced: five meats, five fish dishes, five poultry and game dishes, plus the obligatory paella with all seafood or meats and seafood. The paella is, indeed, a grand presentation of bright coral saffron rice accented with red pimento strips and green peas, robustly flavored by chunks of chorizo and ham, flecked with squid, clams, mussels and big pieces of chicken; it tastes as presentable as it looks. But even better is the seafood stew, zarzuela de mariscos, each sea creature moist and tender, buried in a thick, heavily brandied white wine sauce. Immediate conclusion: Costa del Sol buys its fish very fresh and cooks it very nicely. Filet of sole in white wine with mushrooms, mussels and shrimps reinforced the conclusion. Red snapper, too, though its Spanish version of bearnaise sauce was a bland, oily sludge bearing no noticeable relation to anything French. The same sort of misstep appeared in the chicken with cream sauce and almonds, a salty glue that tried to pass itself off as a real sauce. It is hard to say why those two dishes went so awry, except to guess that the chef has not mastered butter and cream sauces. He also overcooks vegetables, hardly takes them seriously. He redeems himself, however, with Castilian-style rabbit, dark and dense and brandied, the seasonings intricate and the rabbit meat juicy. And the house salads are light and refreshing, sparked with tiny sharp black olives and firm anchovies.

Not a bad batting average, especially in light of the pastries. Brazo gitano, the custard-filled cake roll, is here soft and egg-rich. Fruit tarts have twice been found soggy, but started out as elegant concoctions of apples or peaches with ground almonds and apricot galze in a buttery cookie crust. The flan is appropriately fragile and deliciously caramelized. The final upbeat note is excellent, dark-roasted coffee and a fairly priced bill.

Ordering from appetizer through dessert will bring you more food than you are likely to be able to eat, and washing it down with large pottery pitchers of sangria or a light, fresh Torres Vino Sol at $6, will cost less than $20 a person after tax and tip. Soft Spanish music comes free, and if you stay late enough in the evening, the chef - in sneakers - may even come out to play chess at a corner table. No stiff, formal dining. No hurry-scurry. Costal del Sol is good food and good fun.