Combine jalapenos, garlic, pepper, salt, lime juice and oregano in a blender. Blend until smooth.
Place steak in a shallow pan or large resealable plastic bag. Pour jalapeno marinade over the steak, and turn to coat. Cover pan or seal bag; marinate in the refrigerator 8 hours or overnight.
Preheat an outdoor grill for high heat, and lightly oil the grill grate.
Drain and discard marinade. Grill steak 5 minutes per side, or to desired doneness.
Recipe by Make Mine Gluten Free at https://www.makemineglutenfree.com/jalapeno-steak/