Rub salmon with olive oil. Lay salmon with skin on bottom in the deep dish & coat both sides with salt mixture. Drizzle Cognac over top. Cover with plastic wrap, keep in fridge, & baste frequently (36 to 48 hours). Take out of dish with brine and slice salmon thin diagonally.
Prepare salmon on cracker with mustard sauce and fresh dill.
Keep the remaining salmon in fridge until enjoyed.