Combine cilantro, olive oil, lime juice, garlic, pepper flakes, and salt in a blender; blend until smooth. Pour into a large resealable plastic bag. Add pork tenderloin to the bag, coat with marinade, squeeze out excess air, and seal the bag. Marinate in the refrigerator, 8 hours to overnight.

Combine chicken broth and lemon juice in a pressure cooker. Remove tenderloin from marinade, shake off excess, and reserve remaining marinade. Place tenderloin in broth mixture in the pressure cooker; pour reserved marinade over tenderloin.

Seal and lock pressure cooker according to manufacturer's instructions. Cook over high heat to build pressure until the indicator sounds. Reduce heat to medium; cook for 25 minutes. Remove from heat; let stand for 5 minutes. Place pressure cooker under cold running water to help release pressure before unsealing the lid. Slice tenderloin into medallions to serve.