In a large slow cooker, combine the wine, water, shallot, garlic, dill, parsley, and peppercorns. Squeeze half of the lemon over the slow cooker (watch for seeds!). Slice the remaining lemon half and add the slices to the slow cooker.
Set the slow cooker temperature to HIGH and heat the poaching liquid for 30 minutes.
Reduce the slow cooker's heat to LOW.
Rub a thin layer of salt over the salmon. Place it in the slow cooker, skin side down. Cook on LOW for 1 hour.Tip: After about 45 minutes, start checking on the salmon to see if the flesh starts to flake away.
Remove from the poaching liquid and set drain on a paper towel skin side down.
Serve warm with your favorite sides. Sprinkle some fresh dill and place lemon slices on top for garnish.
Notes
If you use a whole salmon filet, you'll want to cut it into 4 relatively equal portions before cooking.