Step 1

For the chile sauce: Cover the California chiles, guajillo chiles and pasilla chiles with water in a medium saucepan and soak for 2 hours. Add the garlic and simmer until tender, about 30 minutes. Blend small batches at a time in blender, adding some fresh oregano each time. Strain through a medium-mesh strainer.

Step 2

For the stewed tomatoes: Simmer the heirloom tomatoes whole in a large uncovered pot over medium heat until they are broken down and have released some of their liquid, about 45 minutes. Let cool slightly and then puree with an immersion blender.

Step 3

For the chili spices: Combine the oatmeal, cumin, paprika, salt, black pepper, cayenne pepper and red pepper flakes in a bowl. Set aside.

Step 4

For the chili: Preheat the oven to 350 degree F. Mix together the chuck, top round, onion and garlic in a Dutch oven. Cook in the oven, stirring occasionally, until brown.

Step 5

Add the chili spices to the ground beef mixture and cook 20 minutes more. Then add the stewed tomatoes and chile sauce. Cook until an instant-read thermometer register 160 degrees F, about 1 hour.