Red Velvet Cake
["1 (No. 2) box Duncan Hines yellow cake mix", "1 bottle red food coloring", "1 Tbsp. vinegar", "3 1/2 Tbsp. cocoa (sift with cake mix)"]
["Mix cake mix by following directions on box.", "Add remaining ingredients.", "Bake according to directions."]
["cake mix", "coloring", "vinegar", "cocoa"]