1. Preheat the oven to 200 degC. Put an ovenproof pan over a high heat, then add the oil, which will heat up instantly.
2. Carefully lower the pork fillets into the pan, then brown on all sides, seasoning each browned side.
3. Cut the ginger into matchsticks, then add to the pan. Place the pan in the oven, then cook for 10-12 minutes or a little longer if you like your meat well-done.
4. Transfer the pork to a suitable plate to keep warm, then cover with tinfoil. Put the pan back over a moderate heat, then add the butter and spinach leaves, allowing the leaves to wilt slowly into the butter. Stir occasionally to loosen any bits stuck to the bottom of the pan.
5. Cut the pork into 2cm slices, then place on warm serving plates with the spinach at the side.
6. Serve with parmesan baked onions.

To prepare Parmesan Baked onions:

1. Preheat the oven to 180 degC. Peel the onions, then bring them to the boil in a deep saucepan of water.
2. Simmer them for 25 minutes or until tender, then use a draining spoon to remove them from the saucepan. Slice the onions from root to tip and place them cut-side down in an ovenproof dish.
3. Pour the cream over the top, then season with salt, pepper and parmesan. Bake for 25-30 minutes until golden and bubbling.