How to Make It
In a medium saucepan, combine the unchopped tarragon and chives with the water, wine, parsley leaves, scallions, celery, garlic, thyme, coriander seeds, peppercorns, lemon zest and 1 teaspoon of salt. Bring to a boil, then reduce the heat to moderate and simmer the broth for 20 minutes. Strain the vegetable-herb broth into a very large skillet; discard the solids.
Bring the vegetable-herb broth to a simmer. Season the salmon with salt and carefully add the fillets to the skillet, skinned side up. Bring the broth back to a simmer. Cover the skillet and reduce the heat to moderately low. Cook the salmon for 3 minutes, then turn the fillets and add the fresh peas. Cover and cook until the peas are bright green and the salmon is barely cooked through, about 4 minutes.
Using a slotted spoon, transfer the salmon to shallow bowls and scatter the peas on top. Whisk the olive oil into the broth. Pour the broth over the salmon, sprinkle with the chopped tarragon and chives and serve.