Heat 2 tablespoons oil in 10-inch nonstick skillet over medium heat until shimmering. Add shallot, ginger, cumin, and fennel and cook until fragrant, about 15 seconds. Stir in tomatoes and 1/4 teaspoon salt and cook, stirring frequently, until tomatoes have softened, 3 to 5 minutes. Off heat, stir in vinegar and sugar and season with salt and pepper to taste; cover to keep warm. Stir in cilantro and remaining 2 tablespoons oil just before serving.

Makes about 2 cups