Preparation

• Peel and core the apples. Cut them into slices about 1/3 inch thick and put them in a bowl. Sprinkle with 1 Tbs. of the lemon juice and the sugar. Toss well and let stand for 30 minutes.
• Pour 3 inches of oil in a stockpot or Dutch oven, attach a deep-fry thermometer, and set it over medium heat. Heat the oven to the lowest setting. In a medium bowl, sift together the flour and salt. Lightly beat the egg yolks with the remaining 1 tsp. lemon juice and 1/4 cup water. Make a hollow in the center of the flour mixture and pour the egg-yolk mixture into it. Mix well. Add another 1/4 cup water and the butter, beating hard and pressing the batter against the bowl to break up any lumps.
• Beat the egg whites until stiff and fold them into the batter. When the oil has reached 365°F, drain the apple slices well and then drop several into the batter. Pick up the slices one at a time, allow excess batter to drain off, and drop them into the hot oil. Don’t crowd the pot and make sure the oil stays between 350° and 365°F. Cook until the batter is golden brown, about 3 minutes.
• Remove the fritters from the oil with a wire-mesh strainer and let excess oil drip back into the pot. Drain the fritters on a rack set over a baking sheet. Put the rack and the baking sheet in the oven to keep the fritters warm while you fry the remaining apple slices. When all the slices are fried, sprinkle with sugar and serve immediately.