1. Place the sweet potato in a pan and cover with water, bring to the boil, season with salt and add the garlic clove. Cook until the potatoes are tender when pierced with a knife.
2. Drain the potatoes and mash along with the garlic clove.
3. In a tsp of oil, sweat the chilli and ginger then add to the mashed sweet potato.
4. Cut 4 slices from the lemon and lay 2 slices on each of the fish fillets then place in a steamer and cook until the fish is just cooked (approx. 5-7 minutes).
5. Season the mash and add a good squeeze of lemon juice.
6. Serve the steamed fish on top of the sweet potato mash.