Place chiles in pan; flatten with a spatula. Cook 5 seconds on each side or until blackened.
Combine toasted chiles and 2 cups boiling water in a bowl; let stand 20 minutes or until soft.
Place the chile mixture in a blender or food processor; process until smooth.
Heat a Dutch oven over medium-high heat.
Add chopped onion, chopped chorizo, and minced garlic; cook 5 minutes or until browned, stirring frequently.
Add the pureed chile mixture, Swiss chard, and next 5 ingredients (through tomatoes); bring to a boil. Reduce heat, and simmer 30 minutes. Warm tortillas according to package directions.
Serve soup with tortillas; sprinkle with queso fresco.