Chipotle Enchilada Sauce

For the sauce:

onion, diced

olive oil

garlic, minced

crushed tomatoes

canned chipotle chilis in adobo, chopped, plus 1-2 teaspoons of the adobo sauce (depending on how spicy you like it. I used 5 chilis!)

cumin

oregano

chili powder

salt and pepper,