Cut the chicken fillet horizontally into 4 flat pieces, then tenderize each piece with a meat tenderizer. Do not salt yet.
Heat a large frying pan over medium-high heat. Add 4–5 tablespoons of vegetable oil and 25 g of butter, and let them warm for 1 minute until the butter is melted.
Place the chicken pieces in the pan and fry for 4–5 minutes until the first side is golden brown.
Turn the pieces over, season with salt, and sprinkle with pepper mix. Continue frying for another 4–5 minutes until the second side is golden brown and the internal temperature reaches 74°C / 165°F.