Line a baking sheet with foil.
Microwave the nuts on high for 1 minute so they will be warm when you add them to the caramel. Alternatively, heat them in a 200°F oven while you make the caramel.
Pour 1/4 cup water into a heavy 3-quart saucepan. Pour the sugar and salt in the center of the pan and pat it down just until evenly moistened (there should be clear water all around the sugar). Cover the pan and cook over medium-high heat until the sugar dissolves, 2 to 4 minutes. Uncover and cook without stirring until the syrup begins to color slightly, about 1 minute. Reduce the heat to medium and continue to cook, swirling the pot gently if the syrup colors unevenly.
When the caramel is a pale to medium yellow, less than 1 minute more, add the warm nuts. With a heatproof silicone spatula, stir gently and slowly to coat the nuts with caramel. Continue to cook until a bead of caramel dribbled onto a white plate is reddish amber, about 1-1/2 minutes more. Immediately scrape the mixture onto the baking sheet and spread it as thin as you can before it hardens. When the caramel is slightly cooled but still warm, slide the foil with the caramel nuts into a zip-top plastic bag and seal the bag. Cool completely. Chop or crush.
Photo: Scott Phillips