Roasted ~100 g of hazelnuts at 360 °F for 15 minutes. Let the nuts cool to room temperature. Remove the skins by rubbing the cooled down nuts in your hands until most of the skins have come off. Remove as much of the skins as possible off of the hazelnuts.
In a medium saucepan, combine water and sugar over low - medium heat. Stir until sugar dissolves and begins boiling. Stop stirring the saucepan and let it boil on its own. Turn down the heat and let it boil on low (1-2).
The sugar will go through transformations as it becomes caramel. The sugar will begin to form crystals and be completely dry in the saucepan.
The sugar crystals will begin to melt and become a golden brown color. When it's turning a bit darker of a color, it's time to take it off the heat. You don't want to burn the caramel sauce.
Get a baking pan ready with a silicone baking mat lining it. Once your caramel sauce is finished, remove it from heat. Mix the sauce to make the crystals melt all the way through if there's any left in the pot. Pour the hazelnuts and salt into your caramel sauce and mix until they are fully covered.
Pour the hazelnut and caramel sauce onto the silicone baking mat. Let it cool to room temperature, it will solidify.
Break the caramel into smaller pieces. Place them into a food processor. It will be LOUD. Prepare yourself! It's best to do this step with ear protection. Blend on low, then on high. Scrape the sides down and blend until it becomes a paste (a couple of minutes). Set praline paste aside.