Add fennel seeds, coriander seeds and juniper berries to a pan. Place over low heat and cook for about 30 seconds, then remove from the heat and crush them using a pestle and mortar. Finely chop the dill. In a small bowl stir to combine salt, sugar and smoked paprika. Add the ground seeds and berries and zest of one lime, stir to combine.
Sprinkle half of the cure mixture over a baking sheet lined with parchment paper. Place the salmon on top of the cure mix skin side down. Sprinkle the rest of the cure mix over the salmon and press the cure mix into the salmon fillet so it incorporates as much of the mixture as possible. Transfer the salmon fillet to a large vacuum bag, making sure the fillet is covered in cure mix. Vacuum the salmon fillet using a Vacuum machine. We used a powerful Slovenian Vacuum Machine SV2000 from Status Metlika. Place in a fridge for 24 - 48 hours.
Remove the cured salmon fillet from the fridge. Open the vacuum bag and rinse the salmon under cold running water to remove all the cure mixture. Tap dry using a paper towel. Place on a wire rack or large tray and place in the fridge for 1 - 2 hours. Use a very sharp knife to thinly slice the gravlax and serve.
You can serve your Salmon Gravlax immediately or vacuum it again and store it. Store in a fridge for up to 3 weeks or place in the freezer for up to 2 months. Defrost by bringing it to room temperature.