01 - Heat olive oil in a large skillet over medium heat. Add chopped onion and sauté for 2–3 minutes until softened. Stir in minced garlic and cook for 30 seconds until fragrant.
02 - Add ground beef to the skillet. Cook while breaking up with a spoon until browned, approximately 5–6 minutes. Drain excess fat if necessary.
03 - Stir in cumin, chili powder, smoked paprika, dried oregano, salt, and black pepper. Cook for 2 minutes until spices are fragrant. Remove from heat and keep warm.
04 - Combine refried beans with water in a small saucepan. Heat over low heat, stirring constantly until smooth and warmed through.
05 - Preheat oven to 350°F. Arrange tostada shells on a baking sheet. Spread a layer of warm beans over each shell, then top with seasoned ground beef.
06 - Sprinkle shredded cheese evenly over the beef. Bake for 5–7 minutes until cheese is completely melted and tostadas are heated through.
07 - Remove from oven. Top each tostada with shredded lettuce, diced tomatoes, sour cream, cilantro, jalapeño slices, and a squeeze of fresh lime juice.
08 - Serve immediately while tortilla shells remain crisp for optimal texture.