Preheat oven to 300°F. Line two baking sheets with parchment paper or silicone baking mats. In a medium mixing bowl, beat egg whites, instant coffee, vanilla, and cream of tartar with a mixer on high until soft peaks form (tips curl). Add sugar, 1 Tbsp at a time, beating until stiff peaks form (tips stand straight). Fold in chocolate chips. Drop mixture by rounded teaspoon 2 inches apart on the prepared baking sheets. Bake for 20 minutes or until firm and bottoms are very lightly browned. Transfer meringues to a wire rack and let cool.