Wash the leek and then cut into rounds. Peel the carrots and cut into batons. Wash and dice the celery. Wash the fennel, cut in half and remove the core before cutting into slices.
Heat a frying oan and add a little olive oil. Add the carrots, season and sweat until they start to soften. Add the rest of the vegetables and the fennel seeds. Cook until tender and then add the orange juice and the fish stock. Simmer until the stock has reduced by half.
Heat a frying pan to hot. Season the salmon fillets and then add to the pan skin side down. Turn the fish over and cook though. Remove from the pan, wipe out any excess fat and then deglaze with the tomato vinegar. Allow to reduce to a syrup.
Plate the vegetables and then place the salmon on top. Finish with a drizzle of the tomato vinegar syrup to serve.