For New Yorkers who study the bylines of menus, Alex Urena is already a household name. With little fanfare, he has held the reins of numerous kitchens, including those of Bouley, Blue Hill, and Suba. But the word is spreading. Now his name graces the facade of his very own restaurant: Urena, off Park Avenue South.

In the new kitchen, Mr. Urena cooks elaborate – sometimes over-elaborate – symphonies of Spanish flavor, scored for avant-garde instruments like purees and gelees. Fresh from a stint at El Bulli, Spain’s temple of scientific gastronomy, he has clearly mastered a number of creative techniques, evident in dishes like foie gras yogurt and cold-smoked tuna. At times, though, the cooking relies too fixedly on its technical tricks, at the expense of Spain’s sunny, garlicky exuberance. This is most apparent in the dining room, where the menu’s (and the servers’) enumeration of each ingredient (“samfaina brunoise, oyster-juice gelee, smoked-oyster foam”) makes every dish into an intellectual exercise. The tendency is mercifully restrained at the tapas bar up front, where smaller dishes, just as creative but less rambling, have an accordingly heightened impact.

A foie-gras trio ($15) exemplifies the former approach. When the fatty organ is sauteed with a tart kumquat accompaniment, it’s fine and familiar; but a second treatment, where it’s turned into a smear of caramelly “praline,” points out the liver’s bitterness in an unflattering way. The third act of the trio is the best: a blend of foie gras and yogurt that executes a skillful rich/tart balancing act deliciously enough to make one wish the supermarket carried quart tubs of it next to the Dannon. Oyster escabeche ($15) enshrouds raw (i.e., non-smoked) oysters in a smoky froth, a neat way to offer both types of oyster taste combined into one, while cubes of gelled oyster liquor flex an additional flavor muscle. A foamy parsnip puree gives grounding to large, delicate grilled scallops ($14), even as a dab of Spanish herring caviar pulls them in the opposite direction, imparting a marine ethereality to the dish.

Main courses only raise the food’s complexity level and the length of the wearying litanies. At this height of culinary choreography, eating runs a risk of becoming more cerebral than sensual. The palate can’t fully enjoy a roasted flounder ($26) when it’s busy looking for and cataloguing its accompanying “glazed celery root, honshimeji mushrooms, manchego and arugula mousse, grapefruit and elder flower sauce.” At its best, the food transcends its baggage, as in a poached halibut filet ($28) crusted with chicharron crumbs and sauced with a foamy, oniony, creamy essence; or a beautifully tender pairing of lamb leg and chop ($27) with minimal adornment.

In the unfelicitous dining room, a bright yellow tube that focuses attention on the bright but homely kitchen entrance, it’s easy to feel restless, but sitting at the bar gives one a different sense of the restaurant. Six-dollar tapas take the place of $28 entrees, and the ambiance becomes airier and more enjoyable. Bocadillos ($7), a Spanish take on panini, are filled with a choice of cheeses or, better, a punchy pairing of Cabrales blue cheese and sweet, moist shreds of braised rabbit. A couple of those plus a cold-cut platter ($6 a cut, or $19 for four) makes a good modest meal, but a full list of hot and cold tapas is offered, too. Some of these are familiar from the dinner menu: the oyster escabeche ($7), the scallop ($8). Braising strips of pork belly ($8) removes the cloying fattiness that cut often has, leaving a succulent, savory mouthful, which a mildly astringent apple puree with a hint of anise sets off excellently. A wry upscaling of ropa vieja ($7) puts braised pork on little crusts in the company of juicy duck confit, foie gras, and black-truffle sauce.

Fifty reasonably-priced Iberian wines include Portugal’s big, juicy Vertice red ($12/$42), an elegantly austere El Coto Rioja ($8/$34), and the sparkling, seafood-friendly Txomin Etxaniz txakoli ($12/$48). Caryn Stabinsky’s inventive desserts (all $12) almost upstage the rest of the meal: Creations like a bright-fuchsia beet panna cotta with orange salt and chocolate sauce neatly complement Mr. Urena’s elaborations. She has a proclivity for ice creams in white dairy flavors: yogurt, sour cream, buttercream frosting. The latter accompanies a brilliant dessert of fresh puffy doughnuts paired with coffee in three forms: gelee, foam, and glaze.

Cooking and restaurateurship are two separate skills, and deft as Mr. Urena consistently proves himself at the former, the restaurant could use a surer hand when it comes to questions of decor, service, and overall vision. Some slip-ups are a consequence of the restaurant’s youth, but some, like the stiff, pedestrian room, are entrenched. The beautiful, bargain-priced tapas warrant regular visits to Urena, but the entrees, though delicious, can stand to lose a little virtuosity and gain a little substance.

Urena, 37 E. 28th St., between Madison Avenue and Park Avenue South, 212-213-2328.