Heat oven to 350°F. Grease and flour two 9-inch round baking pans or line 28 to 30 muffin cups (2-1/2 inches in diameter) with paper bake cups.
Stir together sugar, flour, cocoa, baking powder, baking soda and salt in large bowl.
Combine milk and lime juice in a bowl and allow to sit for 5 minutes to thicken. Then add eggs and vanilla and whisk together.
Add milk mixture and oil to the dry mix in the mixer and beat on medium speed for 2 minutes.
Sowly pour the coffee down the side of the bowl with the mixer set to it's lowest setting. The batter will be thin. Pour batter into prepared cups. 2/3 full for large liners or cups, 1/2 full for all other cup or liner sizes.
Bake 22 to 25 minutes for cupcakes or until wooden pick inserted in center comes out clean. Cool 10 minutes; remove from pans to wire racks. Cool completely.