Step 1In a heavy-bottomed pan with high sides, place the sugar, lemon juice and one-fourth cup of water. Turn the heat to medium-high and bring the mixture to a boil, swirling the pan occasionally or stirring to maintain even cooking.
Step 2Cook the sugar until it turns a deep bronze, about 8 minutes, then remove the pan from the heat.
Step 3Pour the cream all at once into the hot sugar. Be careful, as the mixture will bubble and froth up. Stir with a wooden spoon until the sauce is smooth and combined and has stopped boiling.
Step 4Add the salt and if you are adding flavoring, stir that in as well.
Step 5Pour it into a glass bowl, cover and refrigerate for 30 minutes or longer. The sauce will cool down, develop flavors and thicken to the right consistency; if you let it cool down completely and it becomes too thick, put it in the microwave briefly or in a metal bowl set over a pan of simmering water until the sauce is a pourable consistency.
Armagnac caramel sauce: Add 1 tablespoon Armagnac while stirring in the salt.
Honey caramel sauce: Substitute 1 tablespoon honey for the lemon juice.
Pomegranate caramel sauce: Add 1 tablespoon pomegranate juice while stirring in the salt.
Banyuls caramel sauce: Add 1 tablespoon Banyuls vinegar while stirring in the salt.