Firefly is the third restaurant concept Russ and Sherry Berger (also of Laurel and Baja Cantina) have tried in this fun space behind Copley Place. I understand why they changed from Café Moka: the hip concept scared off some people without tattoos or skateboards. And I sort of understand why they changed from Hazel’s Cup and Saucer, which they probably did around the time the martini list got longer than the wine list. I’m not sure what they’re doing with Firefly, but at least they won’t need to change the name if they want to try another concept.

As for Firefly’s concept, well, what is an " American bistro " ? I suppose Firefly glows in the dark; most places do, now that we have electric lights. But it is a very useful restaurant to have right near Copley Place, or anywhere else that you might want a really excellent thin-crust pizza, a moderately priced enormous dessert, or a nice dinner you can still afford.

I think one of the pizzas is actually your best appetizer idea. The basic garlic-tomato-cheese pie ($6.95) is built on a tortilla-thin flour crust that gives it plenty of crunch, and the fresh tomatoes are glued in with the cheese and flavored by the garlic. It’s hot, delicious, and easy to eat. Eight slices make an appetizer for up to four.

I suggest this because the breadbasket included chunks of cold, greasy focaccia, and I wasn’t impressed with either salad we tried. The mesclun salad ($3.95/$5.95) was stolen by the garlicky croutons, but the kitchen forgot the cucumbers (some were sent out on another plate), and the slices of freight-car tomatoes were so 1975. The caesar salad ($4.95/$6.95, chicken for another $2) was perfunctory. The corn chowder ($2.50/$3.50) was touted by the waitress, but it tasted mostly of cream, salt, and pepper. Fried calamari ($6.95) were breaded with a lot of cornmeal that fried up crunchy and brown, but greasy. The dip was a tomato sauce full of uncooked wine. I did like the handful of cress on the side.

Things improve quite a bit with the entrées, and the prices are good, too. Pecan-crusted chicken breast ($11.95) offers two lovely scaloppini, crunchy with a nice flavor of caramelized pecans, and a relish of sautéed onions and apples. The side dishes of pan-seared green beans, garlic mashed potatoes, and that handful of cress are all delicious.

Poached salmon ($12.95) is better than the grilled or seared salmon on so many menus now. I’ve never really liked the flavor of burnt fish, and the gentler poaching keeps the salmon juicy even when held. I do think the chef should salt less and hold the pepper, but the dish is otherwise impeccable. The underlying spaghetti squash is sautéed with garlic and tomato for some real flavor, and the two polenta cakes under that are crusty and delectable. The crowning touch of deep-fried laver brings the platter up to date.

Beef tenderloin ($15.95) is a superb steak, as buttery-tender and mildly flavored as any, and nicely dressed with a " chimchurri " sauce. Better to omit the " i " in chimichurri and sharpen up the sauce with a little pepper than to serve the frequently dull parsley sauce and spell it as the Argentines do. The presentation was so vertical as to be funny. The chef inserted a spike of rosemary threaded with a series of onion rings, which brought to mind the neck-elongating rings of the Padaung tribal women on the border of Thailand and Burma. That’s vertical food! Unfortunately, the onion rings had the same corn-meal breading as the squid rings, so the flavor didn’t rise to the appearance. Same garlic mashed potatoes, and why not? Duck-breast slices ($13.95) were prettily fanned out around a mound of wild rice and a contrasting pile of the same cress. Well, if you have fresh, crunchy cress, flaunt it.

The wine-by-the-glass list may be shorter than the martini list, but the Chiarlo Barbera d’Asti ($6.50) is a fine Italian red with the acidity to stand up to all kinds of food. The featured Thomas Mitchell shiraz ($6.50 glass/$16.67 bottle) was quite similar, but with a far-longer-lasting flavor. It was hard to pick up nuances of the wines because they were poured generously into smallish glasses, leaving too little air space to gather aromas. Water is replenished well, and there are slices of lemon in each glass. On the other hand, we actually sent back a glass of Sprite ($1.25) because it was weak and bitter. I don’t think I’ve ever sent back a soda in a restaurant before. It was replaced by a bottled lemon Coke that was fine.

Desserts are all priced wonderfully at $3.95. The brownie sundae is a real enabler. Under-baked and very chocolatey, the brownie was larger than many digital cameras, and served with two small scoops of chocolate ice cream. A linzertorte was smaller, but had the rich, almond crust and full raspberry flavor we hoped for. A special dessert, peanut-butter tart, was mostly a peanut-flavored, cheesecake-rich mousse. This was dipped in chocolate, and there was an underlying layer of banana, but the shortbread crust was too rich for the rest, and seemed heavy.

The rooms are on several levels, with some tables outdoors. Some walls are green, and some could use another coat of paint — perhaps Firefly is overdue for another name change and paint job? Let’s hope not. The unmatched tables (remember when?) are reasonably comfortable, although one of the most comfortable ones, tucked away at the end of a room, trades quiet for lapses in service. Generally, the space is broken up such that one has a sense of privacy but often cannot see a server. And probably they cannot see the diners, either. There’s no solution unless the servers run around a lot. If I’m ever reincarnated, I pray that my many sins against the restaurant industry do not set me up for a dozen lifetimes as a waitress in a place with stairs.

Robert Nadeau can be reached at RobtNadeau@aol.com