Preheat the grill to high.
Combine oil, one teaspoon chipotle powder, and salt in a small dish. Rub into both sides of the steak.
Grill the steak for about 4 minutes per side, until medium rare. Grill the pineapple for about 2-3 minutes per side until lightly charred with dark grill marks. Remove from grill. Allow steak to rest for at least 5 minutes.
Finely dice the pineapple. Combine with red bell pepper, onion, cilantro, vinegar, a pinch of salt, and a dash of chipotle powder. Taste and adjust seasoning.
Slice the steak into thin strips across the grain.
Serve the steak in the warmed tortillas and topped with pineapple salsa.