For the mustard sauce: Place all the mustard sauce ingredients into a mixing bowl and whisk together. Cover and refrigerate.
For the gravlax: Place a couple sheet of plastic wrap over one another. Lay one of the salmon fillets onto the plastic wrap, skin-side down. Cover the flesh of the salmon fillet with the bunch of dill.
In a mixing bowl, combine the remaining ingredients and mix together.
Sprinkle the entire cure mixture generously over the dill topped salmon fillet and top with the other salmon fillet, skin-side up.
Tightly wrap the sandwiched fillets together and place into a resealable plastic bag, removing all the air.
Place the bundle into a baking dish and weigh down with something like a jar of tomato sauce. Refrigerate and cure for 1 day. Turn the bundle over and place “weight” back over the fillets. Continue to cure salmon for another day.
At this point the bundle can be flipped and cured for an additional day or it can be rinsed at this point. (48-72 hour cure depending on desired flavor and texture)
Carefully unwrap the salmon and gently rinse the dill and cure mixture from the salmon surface with a damn and sterile cloth.
Thinly slice gravlax, removing it from the skin as it’s sliced.
Serve thinly sliced gravlax over toast points with a drizzle of whole grain mustard sauce.