1095 Seven Locks Rd., Rockville 340-8900 Hours: 9:30 a.m. to 9:30 p.m. Monday through Saturday; 4 p.m. to 8:30 p.m. Sunday. Prices: Greek items about $4 to $8. Credit cards: None.

How many pizza-sandwich joints are there in Maryland shopping centers? Five hundred? A thousand? Sometimes it seems like a million, all stamped out of the same mold. So when one of them takes the plunge and expands its menu to include a few hard-to-find items, it's an event worth noting.

That's what has happened to Theo's, which now features some Greek cooking in addition to the standard pizza-sub-breakfast routine. The Greek selection is too limited to qualify Theo's as a full-fledged Greek restaurant at this point, and not all the Greek dishes are successful. But if you stick to the ones they do best, you can have a very pleasant dinner here, at a satisfyingly low price.

The one dish not to be missed is the cold appetizer called iman baildi, a slice of eggplant topped with chunky tomato, olive oil and pine nuts and flavored with a touch of cinnamon. It's an irresistible combination. Almost as good for a shared appetizer is the spanakopita, the Greek spinach pie with phyllo wrapper. The spinach filling in Theo's version is excellent, with a zippy flavor and just the right proportion of feta cheese mixed with the spinach. The pastry doesn't have quite the crackle it should, but this is a good pie.

Consider the Greek salad, either as a shared appetizer or an accompaniment, if you're going to have a sandwich. The taramosalata, an appetizer dip made with fish roe and in a potato binder, is tasty, too, but it lacks enough garlic and lemon juice.

A good entree choice is chicken riganato, which is rubbed with garlic, lemon juice and oregano and then roasted. The meat is nicely moist, the flavor is appealing (although, again, more garlic and lemon juice is in order), and the roasted potatoes that accompany the dish are lovely. At $5.95, including a small salad, this is a nice buy, too.

The moussaka is unusually good, with excellent coarse-ground beef, zucchini and eggplant. It's very light, not overdosed with cumin, and topped with a remarkably fluffy bechamel sauce that doesn't reek of nutmeg.

There are several generously portioned lamb shank dishes, among which the best bet is arni youvetsi, made with orzo pasta and a good tomato sauce. Arni agginares, the version made with avgolemono sauce, is a loser. Its sauce is bland and starchy rather than light and lemony. Another bust is the souvlaki. The portion is stingy and the pork is tough and dry.

If you want a pita sandwich, the gyros is fine, not overly greasy, properly garlicky, with a good yogurt-cucumber-mint sauce on the side.

For dessert, head for the baklava. This is a lovely version, crammed with crushed walnuts and cinnamon. (As with the spanakopita, the phyllo pastry is a bit limp, but that's a minor quibble.) The rice pudding is bland and mushy, and the cheesecake has the texture of mortar.