In a sauté pan over medium-high heat place the brown sugar, cinnamon and salt. Heat the sugar until it begins to melt, bubble and begin to smoke. Remove from heat and whisk in the butter and lemon juice turning the mixture into a smooth caramel. Place back on the heat, lower temperature and add apples. Stirring occasionally, cook the apples until they are tender and covered in caramel, about 5 minutes. Remove from heat, set aside to cool.