In a food processor, combine onion, pineapple, garlic, lemongrass, ginger, olive oil, and fish sauce. Mix until smooth. Put meat in a large food container; pour in marinade to coat. Wrap well. Chill for at least 4 hours or overnight. Remove meat from marinade and season both sides with salt and pepper. Cook on grill for best flavor. Makes 5 servings.
Approximate Nutrient Analysis per serving (based on 6 servings and not including salt to taste):
380 calories, 27 g fat, 8 g saturated fat, 100 mg cholesterol, 570 mg sodium, 4 g carbohydrate, 1 g fiber, 2 g sugar, 32 g protein