On a cutting board, cut the tortillas into 24 triangles, about 3/4 inch. In a medium skillet, heat the oil over moderately high heat. Add the tortilla triangles and fry until golden, 1 minute. Using a slotted spoon, transfer the tortillas to a paper towel-lined plate.

In a large, deep skillet, melt 1 tablespoon of the butter. Add the leek and cook over moderate heat, stirring occasionally, until softened, about 4 minutes. Stir in the shrimp, scallops and crab and season with salt and pepper. Add the wine and simmer just until the shrimp are pink, about 2 minutes. Using a slotted spoon, transfer the seafood to a bowl. Add the parsley and the remaining 3 tablespoons of butter to the skillet and simmer until the liquid is reduced to a few tablespoons, about 3 minutes. Return the seafood to the pan and toss to coat.

Spoon the seafood into Chinese soup spoons or shot glasses, garnish with the tortilla triangles and serve at once.

The fried tortilla triangles can be kept overnight in an airtight container. The cooked seafood can be refrigerated for up to 4 hours.