Heat broiler. Place tomatoes, cut side down, on broiler-pan rack. Broil 3 inches from heat until blackened, about 3 minutes (see Roasted Tomato Salsa, www.familycircle.com).
Heat 1 tablespoon olive oil in large nonstick skillet over medium-high heat. Add onion, jalapeño and garlic; sauté 4 minutes. Add chili powder; sauté 3 minutes.
Transfer onion mixture and tomatoes to food processor or blender; puree. Pour into bowl. Add 2 tablespoons oil, vinegar, red-pepper sauce and salt. For best flavor, refrigerate, covered, a few hours or overnight.