IN THEORY, and for those with better self-control, it is possible to have a refined meal at La Moule while spending surprisingly little money.

I have not been able to do so yet.

Each time I've tucked myself into a dark leather corner booth to grab a quick bite from St. Jack chef Aaron Barnett's mussel-heavy menu, I've wound up whiling away a couple of hours of nibbling French food and drinking Belgian beer to a thumping soundtrack of the Stones and Bowie.

St. Jack has always had a great bar area, and La Moule plays on that idea. It transforms the former Savoy Tavern into a two-part experience on SE Clinton—one half a traditional bistro, the other a hidey-hole with psychedelic wallpaper covered with mussels splayed open like hearts. J'adore.

It hints at where to focus your attention on the one-page menu, whose entire middle section is devoted to those black-shelled bivalves. Because of their stringent cleaning needs and propensity to go bad, mussels can be an eater's biggest folly, but La Moule's are among the fattiest, creamiest I've ever encountered, heaped high with a variety of complex broth options.

The best is the Normandy style, a classic approach pairing bacon lardons and cream with acidic cider and Dijon ($16), while the Thai approach ($15) mixes sweet coconut milk with green curry paste and white wine. Two people could easily be sated splitting both plus an order of frites ($5), with a choice of three mayo-based dipping sauces.

But remember, Barnett's also behind the small plates and entrées; so make time for the steak tartare, served aboard a raft of marrow bone that can be scooped along with quail egg onto toast ($13), or the deceptively simple, but wildly crisp butter lettuce salad with radish, avocado, croutons, and Dijon ($9). Go with the rare New York steak with herbed butter for $21 (the $5 addition to make it à la Diane is gilding the lily) rather than the burger ($12), which was on the bland side, despite a triple cream brie and bacon on brioche.

As conversation flows in the bar and you start to dip your fries right into the mussel broth, it's easy to get lost in drink. The menu from partner Tommy Klus (St. Jack, Multnomah Whiskey Library) is replete with stiff brown options like the Black Lodge ($10), with Wild Turkey rye, Cynar, cherry liqueur, Punt e Mes, and orange bitters. La Moule's back bar is also where I first encountered the Kopstootje or "little head butt," a silly twist on liquor with a beer back. It's a tulip-shaped glass overpoured with Bols Genever, a malty, brown Dutch version of gin, paired with an equally malty glass of Upright beer ($9). Drinkers are supposed to bow their head down to the glass to slurp off the excess pour... thus the head butt (or that's what happens if you have more than one).

And this is why it's easy to drop a bit more than you planned at La Moule: While a shared bowl of plump mussels and fries with a drink is more than enough, as "The Jean Genie" plays on and you eye an order of blue cheese croquettes and try a new-to-you Chouffe beer, it's clear everyone else is doing the same—you're all on Continental time now.

Open daily 5 pm-midnight. Kids would be okay in the front café-like area. Full bar, full mussels, can't lose.