Pat salmon dry with paper towels and place in a large glass casserole dish. In a small bowl, combine the salt, sugar and pepper. Drizzle both sides of the salmon with gin/vodka and balsamic, sprinkle with seasoning mix, using your hands to coat the salmon (both sides) completely. Cover the casserole with plastic wrap, place weights on the top (a plate topped with a couple cans works really well) and refridgerate for 3 days. Every day, flip the salmon over and return the weights on top.
Once the salmon has cured for the 3 days (it will be firm to the touch and glossy), remove from the casserole and lightly rinse with cold water. Brush salmon with Dill olive oil before thinly slicing and serving. Place mayo, sour cream, horseradish and dill in a small bowl, whisk to combine. Serve Gravlax with horseradish cream and your favorite bagels and toppings.