Spinach Tostadas with Shrimp and Potatoes

Name: Spinach Tostadas with Shrimp and Potatoes
Ingredients: 2 (10-ounce) packages frozen spinach, thawed; 1 tablespoon finely diced red bell pepper; 1 teaspoon finely diced serrano pepper; 4 cloves garlic, minced; 2 large eggs; 1/3 cup panko bread crumbs; 1/3 cup grated Parmesan; 1 teaspoon freshly cracked black pepper; 1/2 teaspoon salt, plus more for sprinkling; 1/4 teaspoon cayenne; 3 tablespoons extra-virgin olive oil; 2 tablespoons sour cream; 1/2 teaspoon lime zest; 1 tablespoon finely diced shallot; 3 Roma tomatoes, seeded and diced; 2 russet potatoes, cooked in boiling salted water until just fork tender, then cut in 1/2-inch dice; 2 tablespoons capers; 1/2 pound shrimp, shelled, cleaned, cut into 1/2-inch pieces; 1/4 cup low-sodium chicken stock; 1 tablespoon chopped Italian parsley leaves; 2 tablespoons grated feta cheese