For the sauce:
In a small saucepan, heat the olive oil on low heat and sauté the shallots for 2 to 3 minutes. Turn the heat to medium-high, add the wine and reduce the liquid by one half. Remove from the heat. When the mixture has somewhat cooled, add the balsamic vinegar and the mustard. Then whisk in the fresh cream,. Add the dill and capers, season to taste with salt and pepper and set aside.
For the poached salmon:
In a sauté pan deep and wide enough for the salmon fillets, bring the water, wine, lemon juice, lemon zest, onion, carrot, celery, bay leaf, salt and pepper to a boil and boil for five minutes. Strain the ingredients and return the liquid to the pan. Return the liquid to a boil, add the salmon fillets, lower the heat and simmer the fish for approximately 6 to 8 minutes. If the salmon is not completely covered by the poaching liquid, then turn the fish over once carefully in the pan during the simmering process.
Remove the salmon from the pan to a wood cutting board, allow the excess liquids to drain and place the salmon fillets on serving plates. Pour the sauce over the fillets and garnish with lemon slices and parsley.