For best results, ensure the pork is completely dry before searing to achieve a good crust.
If you cannot find blackberry vinegar, a mix of red wine vinegar and a splash of blackberry jam works as a substitute.
The sauce can be made ahead and reheated gently. Add the pork just before serving to keep it tender.
Pairs well with roasted asparagus, garlic mashed potatoes, or a simple green salad.