Creamy Green Sauce - cooking recipe

Ingredients

2 teaspoons olive oil, or as needed
1/2 cup chopped onion
1 jalapeno pepper, coarsely chopped
1 teaspoon minced garlic
3 green tomatoes, coarsely chopped
4 tomatillos, husked and chopped
3 avocados, chopped (optional)
1 tablespoon water, or as needed (optional)
1 1/2 cups sour cream, at room temperature
1/4 bunch fresh cilantro, chopped
1 teaspoon salt

Preparation

Heat oil in a large saucepan over medium heat; cook and stir onion, jalapeno pepper, and garlic until onion is softened, 5 to 10 minutes. Add tomatoes, tomatillos, avocado, and water to onion mixture; bring to a boil. Reduce heat and simmer until tomatoes are softened and liquid has evaporated, about 15 minutes. Remove saucepan from heat and cool slightly.
Blend tomato mixture, sour cream, cilantro, and salt together in a food processor or blender, working in batches if necessary, until sauce is smooth.