In a large skillet with a lid, place the salmon pieces skin side down with the onion, dill sprigs, and about a tablespoon of salt. Cover everything with cold water.
Place on your stovetop and turn on the heat to medium-high. Bring to a boil, then turn the heat down and simmer uncovered for 10-12 minutes, or until salmon flakes apart easily with a fork. Make sure it stays submerged in the water- add more if you need to.
Meanwhile, melt the salted butter (4 tablespoons) and the chives (1 tablespoon) together (I microwaved it for about 20 seconds).
Carefully remove the salmon from the skillet (I used a fish spatula to do this) and serve drizzled with the chive butter and garnished with extra fresh dill.
If you don't have salted butter, just add a pinch of salt in with the chives.
Serving suggestion: serve with boiled potatoes and steamed asparagus, and drizzle the vegetables with some of the chive butter.
Don't waste the poaching liquid. Strain it and save it, in your fridge or freezer, as stock for making seafood or clam chowders, fish stew, etc.
For a dairy-free/paleo compliant version, use ghee instead of butter.
The provided nutrition information does not include any added sodium from seasoning to taste, any optional ingredients, and it does not take brands into account. Feel free to calculate it yourself using this calculator or by adding the recipe to Yummly.