In a large mixing bowl, beat the egg with a mixer for 2 minutes, until bubbly and fluffy.
Add sugar and beat 2 to 3 minutes, until pale yellow and creamy. Add oil and mix until blended. Add milk and vanilla extract; mix until well blended. Sift in the flour and cream of tartar, then mix on low until just combined.

Heat waffle cone maker according to the manufacturer’s directions.

Scoop 1/4 cup batter onto preheated waffle maker set on medium heat. Cook until golden, then carefully place on a clean, folded cloth towel. Roll into cone form and allow to cool. Cover with foil until ready to use. Be sure to follow the manufacturer’s directions for heating and rolling the waffle into a cone.