1. To make the marinade, zest and juice the limes and roughly chop the onion. Add to a food processor along with half the pineapple, 1⁄3 cup water, crushed red pepper, garlic, cumin, oregano, paprika, oil, and . cup cilantro. Process until smooth.
2. Pat the shrimp dry and place in a bowl. Toss with half of the marinade. Cover and refrigerate 1 hour. Reserve remaining marinade to use as a sauce.
3. Remove the shrimp from the refrigerator and drain. Thread onto metal skewers. Heat a gas or charcoal grill to high and grill the remaining pineapple spears until grill marks form, 5 minutes, flipping once halfway through. Transfer to a plate and cover with foil. Grill the shrimp 4 minutes, flipping once halfway through. Transfer shrimp to a plate and remove skewers.
4. Place the tortillas on the grill to warm through, turning once, about 1 min. Arrange the shrimp and grilled pineapple on the warmed tortillas. Drizzle with the reserved sauce and garnish with the remaining
1/4 cup cilantro.
Per serving: 290 calories, 8g fat, 1g saturated fat, 143mg cholesterol, 677mg sodium, 39g carbohydrate, 7g fiber, 8g sugar, 20g protein