1. Heat oven to 250 degrees F. Line two large cookie sheets with nonstick foil.
2. Using a mixer with the whisk attachment, whip egg whites until frothy. Add cream of tartar, lemon juice, vanilla and salt. A little at a time, add sugar while whisking on high speed. Whisk until all sugar is incorporated and stiff shiny peaks are formed. Transfer 1/3 into one bowl and 1/3 into a second bowl. Spoon remaining batter into a quart-size resealable plastic bag. Tint one bowl of batter pink with the food coloring. Sift cocoa over second bowl and fold into batter. Transfer both tinted batches of batter to two resealable plastic bags.
3. Snip a corner from all three bags and pipe dollops of batter onto foil-lined sheets. Bake at 250 degrees F for 1 hour, until dry to the touch. Remove to a wire rack to cool completely.