In a sauce pan, melt the butter and then add in the evaporated milk and sugar. Bring to a boil and cook for 4-5 minutes while stirring.
Remove from the heat and add in the lemon juice, lemon zest, salt and food coloring. Stir until well combined. Allow to cool slightly before serving. It will thicken more as it cools. Makes 3/4 cup syrup.