Combine tomatoes and garlic in bowl and microwave, uncovered, until steaming and liquid begins to pool in bottom of bowl, about 4 minutes. Transfer tomato mixture to fine-mesh strainer set over bowl and let drain for 5 minutes.
Combine jalapeño, cilantro, lime juice, salt, pepper flakes, and drained tomato mixture in blender. Process until smooth, about 45 seconds. Season with salt to taste. Serve warm. (Salsa can be refrigerated for up to 3 days. Cover and microwave briefly to rewarm before serving.)