Rinse the oranges, limes, chiles and cilantro, you will be using them peel and all.
This recipe calls for whole oranges but, if you would prefer to use only the juice and the zest, this is the time to zest and juice the oranges and set aside.
Cut oranges and limes into wedges, remove stems from jalapenos or chiles of your choice then, cut in them in half. Remove seeds to reduce heat, if desired.
Take a large handful of cilantro and chop it into pieces about 2 inches long. This is a good recipe for cilantro stems. Remove skins from garlic.
Place orange wedges (or juice and zest), limes, jalapeno or chile, cilantro and garlic into your food processor and pulse into a chunky paste
Drizzle the oil and vinegar in as you pulse the ingredient
Pour marinade into a zip top bag or non-reactive bowl (glass or plastic works well)
Add meat to the bag and cover completely with marinade.
Marinate for in the refrigerator for 2 hours or up to 8. Do not marinade for longer than 8 hours or the citrus will break down the fibers of the beef.
Remove beef from bag and remove excess marinade. Season with salt and pepper.
Preheat an outdoor grill, skillet or grill pan to medium high. Brush with a few tablespoons of oil. Sear the beef for 2 to 3 minutes on ALL sides. The beef should stay medium rare in the center. Rest for about 15 minutes. Slice beef into 1/4 inch thick slices.