Preheat the oven to 350°F (175°C). Arrange the Tostada Shells on a baking sheet and warm for 5–7 minutes until crisp and fragrant; set aside.
Warm the Refried Beans in a small saucepan over medium heat, stirring in a splash of water or broth to reach a spreadable consistency. Season to taste with Salt and a squeeze of Lime, then keep warm.
Prepare the toppings: shred the Lettuce; dice the Tomato; slice the Avocado and toss lightly with a little lime juice to prevent browning; crumble the Queso Fresco; thinly slice the White Onion and the Radish; chop the Cilantro; and drain the Pickled Jalapeños.
To assemble, spread a generous layer of the warm beans onto each tostada shell.
Top the beans with shredded lettuce, diced tomato and avocado slices, then sprinkle with crumbled queso fresco. Add a few thin onion and radish slices and a couple of pickled jalapeño rings for bite.
Finish each tostada with a drizzle of Mexican Crema and a spoonful of Salsa Roja. Scatter chopped cilantro, adjust seasoning with more salt if needed, and squeeze additional lime over the top to taste.
Serve immediately so the shells stay crisp. Enjoy these tostadas as a light meal or as part of a larger spread.
