Sontaya, in the sprawling St Regis complex on Saadiyat Island, offers an arriving diner all the upscale charm we expect - but do not always quite get - from high-end hotel restaurants.As Sontaya offers South-east Asian cuisine, this takes the form here of sleek Asian-contemporary decor, a multinational staff to match, water views (in daytime, anyway) from every table and soothing Far Eastern elevator music. But these pleasing elements fade into the background when your food arrives. The menu here is a short but remarkably rewarding choice of mouth-watering cookery, though it comes at eye-watering prices. \"South-east Asian\" here means mainly Thai, and the chef Komsan Thongchaiprasit has added Thai touches to a cosmopolitan variety of raw materials, from Omani lobster to Wagyu short ribs. We began with an appetiser platter (for two) with some familiar items: competent chicken satay, savoury thod mun pla fish patties, deep-fried shrimp and panko-crumbed spring rolls filled with a shrimp-crab-squid mixture. There was also a new (to us) \"pomelo salad\" - no greens, but mixed shreds of dried coconut and fried red onion with tiny dried shrimp and the Asian citrus fruit pomelo, individual cells of it without segment membranes, all in a light tamarind sauce. This memorably successful melding of flavours and textures is also served, we were told, as a garnish with soft-shell crab. Omani lobster appears on the menu in a couple of forms, one being a large portion of out-of-the-shell morsels audaciously paired with a thick, tangy tamarind reduction. This sauce was delicious in itself but, to my mind, a little stronger than the shellfish could handle. My friend, however, found the combination quite successful. This dish comes with no vegetables except a garnish of dried coconut with the merest threads of carrot and leek. Short ribs of Wagyu beef arrived paradoxically boneless, and posed a minor ethical/medical dilemma. Long slow braising tenderises the cut and permits the slipping-out of the rib bones, but the process leaves behind, along with the moist beefy meat, some unctuous blobs of the flavour-bonanza fat for which Wagyu is known. Few doctors recommend beef fat … let\'s just say dinner-plate discipline is an admirable ideal. The Thai-herb sauce atop the beef - a purée including lemongrass, ginger-like galangal, Kaffir lime leaves and star anise - added just the right kick. The dish was served with baby asparagus spears and carrots, along with black mushroom pieces and chunkier wedges of steamed chayote, a Mexican import to Asian cuisine. We added a side dish of morning glory, because who can resist a name like that? The leaves and stems of this South-east Asian green (sometimes called water spinach) had been wilted and served in a dilute soy sauce with garlic and a suspicion of palm sugar. Glory indeed. Desserts were up to the standard already set. Pineapple beignets were nine cubes of that fruit, each dipped in a sweetened batter and deep fried, served with a citrus dipping sauce. Créme brûlé was admirably browned but the \"green tea spaghetti\" garnish let us down: it proved to be pale-green biscuit in the shape of tangled linguine and not really tasting of tea. Sontaya has been open four months but was not busy the weeknight we visited, and we were told that lunchtime is usually quiet. This place deserves better. Service was attentive, as you might expect when a restaurant is uncrowded, and there was a bonus this night: the chef Komsan came by our table and chatted about Asian food with the relaxed contentment of a man rightfully proud of his menu. from the national.