Clean the brussels sprouts. Soak, trim the stem and finely slice them. Place to the side.
Preheat the oven to 350 degrees and place the nuts inside. Roast until golden around 15 minutes. Remove and let cool, then rub in a towel to remove the skin and then roughly chop them.
In your serving bowl, add the finely chopped shallots, garlic, dijon, lemon zest, lemon juice, vinegar, honey and season well with kosher salt and cracked black pepper. Whisk together and slowly stream in the extra virgin olive oil. Check for seasoning and then add in the sliced brussels, chopped hazelnuts and then grate over the gruyere. Finish with cracked black pepper. Keep untossed until you are ready to serve.