Mix together the tamari, zest and juice of the orange, ginger, garlic and spring onions in a shallow glass ovenproof pie dish. Add the salmon, cover in cling wrap and marinate in the fridge for 30 minutes turning occasionally.
Uncover the dish and arrange the orange slices on the top.
Bake for 10-15 minutes until the fish is firm to the touch.
Arrange the salad leaves on the plates and top with the salmon. Pour the cooking juices over the top of the salmon.