Marinate shrimp: Combine 2 teaspoons chipotle with half of lime juice and half of garlic. Season shrimp with salt and toss with chipotle-lime mixture. Set aside.
Prep beans: Rinse and drain beans. Combine beans with red wine vinegar, scallions, cilantro, remaining garlic, 1 teaspoon chipotle, 1 tablespoon olive oil, and 1 teaspoon salt. Set aside.
Make yogurt: Stir together yogurt, lime zest, remaining lime juice and ½ teaspoon salt. Set aside.
Make tostadas: Heat 1/4-inch neutral oil (about ¾ cup) in a small skillet over medium-high. Add tortillas one at a time and cook until crisp, about 30 seconds a side.
Cook shrimp: Remove all but 2 tablespoons oil from skillet. Add shrimp and cook, stirring, until just cooked through, about 2 minutes.
Assemble: Spread lime-yogurt on tostadas and top with black beans, shrimp and remaining cilantro sprigs. Enjoy!