Combine all ingredients except lime zest and coconut flakes into a microwave safe mug. Stir with a small whisk until batter is smooth. Make sure you get all the flour, sometimes it gets stick around the edges of the mug. Briefly mix in coconut flakes and lime zest.
Microwave the cake for about 1 minute. Top of cake should be dry and look finished. Top with additional lime zest before eating.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.