Step 1 Grease a baking sheet and set aside.
Step 2 Combine the sugar, salt, water and corn syrup in a non-aluminum or heavy saucepan and bring to a boil. Cook until a candy thermometer inserted in the mixture reaches 236 degrees. Remove from the heat and add the marshmallows, stirring until melted. Add the peppermint and the walnuts and stir gently until the mixture is creamy and the nuts are well-coated.
Step 3Pour the nuts onto the baking sheet and separate using 2 forks.