Combine half of the oil with the honey, mustard, thyme, salt and pepper in a large bowl or dish. Add the pork fillet and cover with the mixture on all sides. Let the pork marinate in the mixture for 15 minutes or so to come to room temperature.
Preheat the oven to 200 C / 180 C Fan / Gas 6.
Heat the remaining tablespoon of olive oil in a heavy ovenproof frying pan (I used cast iron) over medium heat. Once oil is hot, add the pork fillet and brown for 5 minutes on one side. Flip over, then transfer to the preheated oven.
Roast for 20 to 25 minutes, until no longer pink in the centre. Let rest for 5 minutes before slicing and serving.