In a white mixing bowl, whisk together the mayonnaise, 1/4 cup finely chopped cilantro, 1 tablespoon lime juice, the grated garlic clove and 1/4 teaspoon salt until smooth and pale green. Cover and refrigerate until step 9.

In a second white mixing bowl, toss the sliced cabbage with the chopped kimchi, 2 tablespoons kimchi brine, 1 tablespoon lime juice, the sliced scallions and 2 tablespoons cilantro. Massage the cabbage with your hands for about 30 seconds, until it softens and turns glossy; set aside at room temperature.

Pat the shrimp completely dry with paper towels and place them in a third bowl. Add the olive oil, 1 tablespoon lime juice, the lime zest, chili powder, cumin, cayenne if using, minced garlic and 1/2 teaspoon salt, then toss until every shrimp is coated in the deep red marinade.

Let the shrimp sit at room temperature for 10 minutes so the chili and lime season the flesh all the way through; use this time to lay the mini tostada shells out on a platter so they come to room temperature evenly.

Heat the cream enameled cast iron skillet over medium-high heat for 2 minutes, until a drop of water skitters across the surface. Add the shrimp in a single layer and cook undisturbed for 90 seconds, until the bottoms turn solid pink.

Flip each shrimp with tongs and cook for 60 to 90 seconds more, until the flesh is fully opaque, curled into a loose C shape, with lightly charred edges. Transfer the shrimp to a wooden board.

Let the shrimp rest on the board for 5 minutes to stop the cooking, then roughly chop them into halves so each tostada gets two or three pieces rather than one large one.

Spread about 1 teaspoon of the cilantro mayo over each tostada shell with the back of a spoon, reaching to the edge so every bite gets some.

Top each shell with 1 tablespoon of the kimchi slaw, then 2 to 3 pieces of the chopped shrimp, pressing gently so the toppings sit flat and do not slide off.

Finish each tostada with a thin slice of avocado, a small drizzle of the remaining cilantro mayo and a cilantro leaf. Arrange on the platter with lime wedges tucked between them and serve right away, while the shells are still crisp.