Heat 1 teaspoon of the olive oil in an 8-inch skillet until shimmering. Add 1 tablespoon of the diced red onion and 1/2 tablespoon of the minced jalapeño and cook over moderately high heat, stirring constantly, until the onion is golden, about 4 minutes. Add the coarsely chopped tomatoes and the hot water and cook, stirring, until the tomatoes are just softened, about 3 minutes. Transfer the mixture to a blender or food processor and puree until smooth. Strain the sauce through a fine sieve set over a bowl, pressing on the solids. Stir in 1/2 teaspoon of the lime juice and season the tomato sauce with salt and pepper.