Spicy, sour, salty, and sweet: In Thailand, the perfect meal offers all four tastes. And with its extensive menu, Brown Sugar Café furnishes plenty of options for creating the consummate Thai dinner. Now that a second, larger location on Commonwealth Avenue has joined the charming original spot in the Fenway, the options have doubled. Specialties are all over map, from comforting dishes for fire-averse tongues (such as the pineapple fried rice, flaky and aromatic steamed ginger bass, and sweet tamarind duck) to more incendiary plates of chili scallops with bamboo shoots and scallions. Try the stir-fried beef with macadamia nuts, and wash it down with a Singha beer.