Appetizers: pro forma. Desserts: ex post facto. The big white house on Montauk Highway devotes itself to what's unquestionably the Main event -- steak.

21 Main expertly lets you see red, plus pink and black-and-blue, searing, at last count, seven generous cuts of beef.

They're all served with easygoing style in a conservatively appointed dining room where you won't be distracted from consuming a month's worth of protein in a single sitting.

Unlike too many of Long Island's steakeries, 21 Main is an orderly, unpretentious restaurant, free from the streaks of brusqueness and self-importance that marble the genre.

It's the offspring of Lovin' Oven caterers. Veterans recall this address as housing other eateries over the years. But the carefully calibrated 21 Main is the most ambitious.

You'll enjoy a starter of crisp and tender calamari, sparked with sweet cherry peppers, roasted garlic and a side of cilantro chutney. The house's tuna sashimi may not make you forget the local Japanese eatery, but it's fresh and good.

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So's the pan-seared crab cake with sauce remoulade. But St. Louis-style pork spare ribs can be tough going, slathered with a dull bourbon barbecue sauce. And clams casino are chewy. You can skip the bland lobster bisque, too. 21 Main's straightforward shrimp and crab cocktails make that easy, as does an opener of lush, butter-poached king crab legs.

You could fill up with the iceberg lettuce-and-tomato salad, capped with Gorgonzola-and-chive dressing; or an iceberg-romaine union with spiced walnuts, tomatoes, apricots and blue cheese. There's also the familiar tomatoes-and-onions combo.

But pace yourself and tell anyone at your table to do the same. Then, pick the excellent T-bone steak for two, a 40-oz. slab with an au poivre bite and Gorgonzola cheese for just enough excess. It's grand.

The heroic bone-in rib-eye, weighing in at 32 ounces for one unbuttoned appetite, competes with flair. You'll savor the juicy sirloin, and relish sliced hanger steak with sauteed onions and mushrooms. Filet mignon with a garlic-herb demi-glace doesn't exactly retreat, either.

Dissenters can stick with a standard steamed lobster; pan-seared tuna boosted by tapenade, the olive-driven Provencal spread; and roast chicken with mustard sauce.

There should be unanimity about the blunt, a la carte side dishes. Creamed spinach flecked with pancetta, whipped potatoes, a zeppelin-size baked potato, and mild macaroni-and-cheese make first claims.

Desserts are uneven. The Smores cake slices somewhere between parchment and cardboard; and the crème brûlée is basic. But the house cheesecake and flourless chocolate cake are sturdy selections, with the caramel-pecan torte suitable for mortar.

Or you could consider another investment: they have steaks to go.