2. Increase the heat to high, add the wine, lemon juice, tarragon, sun-dried tomatoes and artichoke hearts and simmer for 1 minute.
3. Season the salmon fillets with salt and pepper and add them to the pan with enough water to cover. Bring the liquid to a boil and adjust the heat so that the mixture simmers. Cook for 12 to 15 minutes, until the salmon is just cooked through. (Thinner fillets will take less time, while thicker fillets will take a little longer.)
4. Remove the salmon from the pan and set aside. Continue to simmer the cooking liquid until it has reduced by half.
5. Divide the watercress among 4 plates. Place the salmon on top of the watercress, garnish with sun-dried tomatoes and artichoke hearts and drizzle the hot cooking liquid over the salmon.