Preheat oven to 350 degrees F. Line two baking sheets with parchment paper. In a large bowl, beat egg whites, lemon juice and salt with an electric beater until soft peaks have formed, about 2 minutes. Begin to beat in sugar, a few tablespoons at a time, until egg whites are very stiff and glossy, about 2 minutes longer. When you pull beater out of whites, peaks should hold their shape. Gently fold in coconut flakes with a rubber spatula. Drop batter by the tablespoon onto prepared cookie sheet. Let cookies bake until firm on the outside and slightly golden, 15 minutes.
