In heavy bottom pot or Dutch oven, heat 1 tablespoon olive oil over medium high heat. Add the chopped 2 medium yellow onion and sauté, stirring occasionally, until slightly brown and tender, about 5 minutes. Add the chopped 4 cloves garlic, 1/2 teaspoon ground oregano, and 1/2 teaspoon cumin and sauté for another minute. Add the 1 tablespoon flour and stir well. Cook the flour with onion and garlic until fragrant, stirring frequently, about 2 minutes.
Add the 1 pound roasted hatch green chiles, 3 small tomatoes, and the 4 cups chicken stock. Stir well to combine and scrape bottom of pan to ensure flavors are fully mixed. Bring to a boil, then reduce heat to low and simmer for 20 minutes.
Remove from heat and blend until smooth in blender. Add salt and pepper to taste.
Serve on enchiladas or breakfast burritos.
Notes
Recipe makes about 8 cups of enchilada sauce.Can be frozen in airtight containers for future use.