Position a rack in the middle of the oven and preheat to 400 degrees. Line a large sheet pan with foil, if desired.

Using a pastry brush or your fingers, lightly moisten each tortilla with the water on both sides. Then, lightly brush each tortilla with the oil on both sides, using more, if needed. Arrange the tortillas in a single layer on the prepared sheet pan; some overlap is okay. (If using 6-inch tortillas, you may need to do this in two batches, or use two sheet pans with racks in the upper and lower thirds of the oven.)

In a small bowl, stir together the cream cheese, the pickled jalapeños, and cilantro, if using, and the garlic powder. Using a small spoon or your fingers, stuff each shishito half with 2 to 3 teaspoons of the cream cheese mixture.

Place 2 of the stuffed pepper halves in the center of each tortilla. Sprinkle about 2 tablespoons of the cheese over each pepper, letting some of it fall on the tortilla as well.

Bake, rotating the pan from front to back halfway through, for 10 minutes, or until the cheese is melted and bubbly and everything is hot. (If using two sheet pans, you will need to rotate the sheet pans from front to back and top to bottom.) Sprinkle with additional cilantro, if desired, and serve immediately.