Cover your fillets with the rye flour. You may have extra left over. Whatever flour doesn’t stick to the fish can be discarded. Put a pan on medium-high heat. Size up how many fillets you will be able to sear at once. You may need to do more than one shift, but only use 1 tbsp butter per each fillet. Once the pan is very hot, place your fillets on the butter. Each side will take about 3-5 mins, depending on your heat and the size of the fish. Be very careful when flipping the fish over; they will be very tender!
Fill a large saucepan with water and bring to boil. Place the potatoes in the water and bring down to medium heat for about 20 minutes, or until your fork easily pokes into a spud. Drain the potatoes and mix with the butter, dill, and salt.
Mix all the sauce ingredients together in a small container or jar. You can save this in the fridge for about a week (unless the sour cream expiration date is sooner).