In medium bowl, stir together black beans, tomato, onions, cilantro, Adobo, lemon juice and olive oil until well combined; cover and set salsa in refrigerator until ready to serve.
Place chiles in medium bowl and cover with hot water. Let sit for about 15 minutes. Transfer chiles and 3 tablespoons soaking water to blender. Add lemon juice, vegetable oil, Adobo, cumin, garlic and oregano to blender. Blend on high speed until smooth, about 1 minute. In bowl, combine chile mixture with shrimp; cover and chill in refrigerator for at least 15 minutes.
Meanwhile, heat ¼” corn oil in small skillet over medium-high heat. Once oil is hot, but not smoking, add one corn tortilla. Fry, flipping once, until tortilla is golden brown and crisp, about 1 minute per side; transfer to paper towel-lined tray to drain. Repeat with remaining tortillas.
Heat grill or grill pan over medium-high heat. Add reserved marinated shrimp and cook, flipping once until shrimp golden brown on both side and center is opaque, about 2-3 minutes per side; transfer to plate.
To assemble tostadas, spread heaping spoonful of warmed refried beans onto each fried tortilla, if desired. Spoon reserved salsa on each tortilla and top with two or three shrimp. Serve with lime wedges.