Pambazos with Potatoes and Chorizo

Name: Pambazos with Potatoes and Chorizo
Ingredients: 4 dried guajillo chiles, seeds removed, torn into 1-inch pieces; Kosher salt; 2 medium russet potatoes, scrubbed; Freshly ground black pepper; 6 tablespoons vegetable oil, divided; 1 4-ounce link fresh chorizo, casing removed; 2 telera, bolillo, or large sub rolls; ¼ cup mayonnaise; 2 cups shredded romaine lettuce; ½ cup crumbled queso fresco; plus more for serving (optional); ⅓ cup crema or ¼ sour cream mixed with 1 tablespoon water; plus more for serving (optional)