Preheat dutch oven or other large pot over medium heat.
Drizzle a small amount of olive oil in the pot (just enough to keep the veggies from sticking).
Add onion, garlic, and bell pepper. Cook until they begin to soften, stirring occasionally.
Stir in spices and 1 tsp salt. Continue to cook, stirring frequently so the spices don’t burn.
Once the onions look caramelized, add the crushed tomatoes and stock.
Bring to a boil, then reduce to a simmer.
Let it simmer for about 20 minutes, then puree everything using an immersion blender. (If you’re using a regular blender instead of an immersion blender to puree it, wait until the end to puree it and let it cool first. Blending something hot in a blender can be hazardous.)
Serve and top with shredded cheese and sour cream as desired.