1. Prepare the marinade by blending the red chili pepper, garlic, soy sauce, balsamic vinegar, and olive oil in a blender or food processor until smooth.

2. Place the pork fillet in a large zip-top plastic bag or a shallow dish, then pour the marinade over the pork, turning it to coat evenly. Seal the bag or cover the dish with plastic wrap and refrigerate for at least 2 hours or overnight.

3. Remove the pork from the marinade, letting any excess liquid drip off, then sprinkle both sides of the pork with smoked paprika, salt, and pepper.

4. Preheat a grill or skillet over medium-high heat, approximately 200°C or 400°F. Cook the pork for 5-7 minutes per side, or until it reaches an internal temperature of 63°C or 145°F. Let the pork rest for 5 minutes before slicing and serving.