Slice the tomatoes in half and pack in the bottom of a roasting pan or oven-proof dish. Season with salt and pepper and some of the thyme. Season the pork steaks and pack on the tomatoes.
Pour over the balsamic vinegar and the olive oil and roast in the oven for 60-80 minutes.
Halfway through the roasting time, turn the pork steaks over o that they roast on both sides. The meat is done when the tomatoes, vinegar and oil have made a delicious sauce in the bottom of the pan.