Combine avocado, lime juice, and salt in a medium bowl. Cover surface of guacamole with plastic wrap.
Heat a medium saucepan over medium heat. Add oil; swirl to coat. Add garlic; cook 1 minute. Stir in vegetable broth and beans. Reduce heat to medium-low; cover and cook 5 minutes or until thoroughly heated. Remove pan from heat; mash beans to desired consistency.
Spread about 1/4 cup bean mixture on each tostada shell. Top each with 2 tablespoons cheese, about 1/3 cup guacamole, 1/4 cup lettuce, and 2 tablespoons Fresh Salsa. Serve immediately.
Tip: You can make things even easier on yourself by purchasing store-bought salsa and guacamole if you can't find ripe avocados.