Fresh snapper is paired with a delectable sweet-sour sauce and a lively parsley salad in this speedy supper inspired by the Saudi Arabian dish samak bil sabbar.
Place tamarind in a medium bowl and cover with hot water. Let soak for 15 minutes; mash tamarind. Strain through a sieve, pressing on solids and scraping the bottom of the sieve to remove pulp. Discard the seeds and set strained liquid aside.
Heat oil in a large saute pan over medium-high. Add onion and garlic and cook, stirring often, until golden, 5 to 8 minutes. Stir in tomato, sugar, coriander, cumin, cinnamon, 1/2 teaspoon salt, 1/2 teaspoon pepper, and reserved tamarind liquid. Simmer for 20 minutes, stirring occasionally, until sauce is thickened. Add more water if sauce becomes too dry. Stir in 1 tablespoon butter and season with salt and pepper; keep sauce warm.
Season fish with salt and pepper. Melt remaining 2 tablespoons butter in a large nonstick skillet over medium-high heat. Sear fish skin-side down, turning once, until cooked through, 2 to 3 minutes per side. Spoon sauce over fish and serve with parsley salad.