- 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
- 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.