For the fish sticks: Heat about an inch of oil in a heavy saucepan over medium-high heat until a deep-fry thermometer inserted in the oil registers 360 degrees F.
Heavily sprinkle the fish sticks on both sides with salt and pepper. Form an assembly line with the flour, whisked eggs and panko breadcrumbs in separate shallow bowls. Dredge the fish sticks first in the flour, making sure to remove any excess, then in the egg wash and finally in the panko.
Fry the fish until golden in color, about 3 minutes per side. Set on a paper towel to drain the excess oil.
For the grilled pineapple salsa: Prepare a grill to medium-high heat.
Put the pineapple slices on the grill and cook until tender and grill marked, about 2 minutes per side. Transfer to a cutting board and chop. Put the pineapple in a medium bowl and stir in the cilantro, lime juice and jalapenos. Season the salsa with sugar, salt and pepper. Serve warm or at room temperature.
For the ancho crema: Add the sour cream, ancho chile powder, lime juice and 1 tablespoon of water to a bowl. Whisk together until combined. If necessary, thin the mixture out with more water until it is a thin, drizzling consistency.
For serving: Heat the corn tortillas directly on a gas burner on medium-high heat, about 30 seconds per side.
Evenly distribute the fish sticks among the warmed tortillas. Garnish with cabbage and grilled pineapple salsa, then drizzle the ancho crema on top.