This is an ideal way to prepare salmon – cooked slowly surrounded by a moist heat. Lentils and beets can be left to cook all day, while the salmon takes only 25 “walk away” minutes once you get home. Use a large 5- to 7-quart slow cooker to accommodate all six portions of salmon. Smaller 21/2- to 3-quart slow cookers can be used but will only accommodate four fillets. If you’d still like to prepare the entire six-fillet recipe in a smaller cooker, try layering the pieces of salmon on top of one another between parchment paper and extend the cooking time by about 7 minutes, until fish is opaque in center.