Heat sugar and water in a small saucepan over high heat, swirling, until sugar dissolves. Bring to a simmer, and cook, swirling occasionally, until medium amber, about 4 minutes.

Add hazelnuts and salt and stir for 1 minute to coat.

Pour mixture onto a baking sheet lined with parchment or a nonstick baking mat and immediately separate nuts using two forks so that each stands alone on sheet. If caramel thickens as you work, return to heat briefly.

Let cool then break apart.