Cook the Beef : Heat a large skillet over medium-high heat. Add ground beef and cook, breaking it up with a spatula, until browned, about 5–7 minutes. Add chopped onion and garlic; cook until softened, about 2–3 minutes. Stir in chili powder, cumin, smoked paprika, salt, and pepper. Add beef broth or water and simmer for 3–4 minutes until flavors meld and liquid reduces slightly.
Prepare Refried Beans : In a small saucepan, heat olive oil over medium heat. Add refried beans and cumin. Stir to combine and heat until warmed through, about 3–5 minutes. Adjust seasoning with salt if needed.
Assemble Tostada Salad : Spread a layer of refried beans on each tostada shell. Top with a generous portion of seasoned beef. Layer shredded lettuce, diced tomatoes, red onion, cheese, avocado, and olives as desired. Garnish with fresh cilantro and serve with lime wedges and salsa or hot sauce.