In a blender, combine the peppers, garlic, pepper, salt, lime juice and oregano. Blend until smooth.
Pour the marinade in a gallon-size zippered bag.
Add the sirloin steaks.
Seal the bag and refrigerate up to 24 hours, but for at least 4 hours.
Heat a skillet with the olive oil over medium heat.
Add the steaks to the skillet. Cook for 5-6 minutes, then, using a spatula, turn the steaks and cook for an additional 5-6 minutes, or until the steaks are at the desired doneness. Medium Rare: 145 degrees; Medium: 160 degrees; Well Done: 170 degrees.
Remove steaks from the skillet, place them on a plate, and cover them with foil. Allow the steaks to rest for 3 minutes before serving.
When the steaks are done, top each steak with a large spoonful of pineapple salsa.