1. Whisk together 60ml (2 fl oz) of soy sauce, 30ml (1 fl oz) of balsamic vinegar, 30ml (1 fl oz) of olive oil, and some chopped fresh herbs in a small bowl.

2. Place a pork tenderloin in a large ziplock bag or a shallow dish, and pour the marinade over it. Seal the bag or cover the dish with plastic wrap. Refrigerate for at least 2 hours or overnight.

3. Preheat the oven to 200°C (400°F). Remove the pork from the marinade, letting any excess liquid drip off.

4. Heat 15g (1 tbsp) of butter in an oven-safe skillet over medium-high heat. Sear the pork for 2-3 minutes on each side, then transfer the skillet to the oven and roast for 15-20 minutes or until the internal temperature reaches 63°C (145°F).

5. While the pork is cooking, prepare the potato salad. Boil the diced potatoes until tender, then drain and let cool. Mix the mayonnaise, sour cream, Dijon mustard, salt, and pepper in a bowl. Add the cooled potatoes, chopped fresh dill, and mix well.

6. Let the pork rest for 5 minutes before slicing it thinly against the grain. Serve with the potato salad and garnish with lemon wedges, if desired.