2. Fry the bacon in a large frying pan or wok until crisp and golden brown and drain on kitchen towel.
3. Stir-fry the marrows, broccoli and beans and garlic for several minutes in the same wok. Add the stock, balsamic vinegar and sugar and let it cook for 3 minutes. Remove from the plate and stir in the basil.
4. Divide the stir-fried vegetables between four plates, spread the wholegrain mustard over the steak and cut into slices. Divide the steak slices between the plates and sprinkle the bacon on top. Serve immediately.