Ingredients

• 2-3 pasilla chiles
  
• 28 ounces fire-roasted tomatoes, diced
  
• 4 garlic cloves
  
• 2 quarts vegetable stock, divided
  
• 1 tablespoon olive oil
  
• 1 white onion, chopped
  
• 1 tablespoon dried oregano
  
• ¹/₂ teaspoon ground cumin
  
• 6 tablespoons Mexican crema or sour cream
  
• 3 tostadas or handful of tortilla chips
  
• 2 avocados, sliced