1/4 teaspoon cayenne pepper or 1/2 teaspoon dried crushed red pepper flakes (more if you like it really spicy)
4 garlic cloves
1 jalapeño pepper
Roughly chop the 3 cups of cilantro (thick stems removed)
Place in a food processor with the remaining ingredients and pulse until chopped. You can puree the mixture if you prefer a smoother consistency. Cover all sides of the meat with the marinade and store in the refrigerator for about 3 hours or overnight.
Wipe off excess marinade and season the meat with salt and pepper before grilling, broiling or pan frying to your preferred doneness. Bring the refrigerated Chimichurri sauce to room temperature prior to serving. I like to add a little more salt to the finished sauce as well.