Peel the lemons, removing just the yellow part without the pith. Blanch the peel in lightly salted, boiling water. Refresh, then dehydrate at 105 degrees F for about 48 hours. Crush the dried peel to a fine powder, sift and mix with the fleur de sel in a proportion of 1/2 teaspoon lemon powder to 2 1/2 tbsp salt. Keep in a dry place This lemon salt is ideal as a condiment for foods that need a salty, citrus touch.
Slice the potatoes very thin, about 0.05" thick. Place in water and change the water three or four times to remove the starch. Dry well with a cloth. Heat oil in a deep frying-pan and fry the chips, a few at a time, keeping them separate. When fried, remove and place on absorbent kitchen paper. Sprinkle with lemon salt. Leave to dry at 195 degrees F for 3 hours.
These chips make a magnificent, easy-to-serve appetizer. When dry and crisp and perfumed with lemon, they are irresistible.