In a large microwave safe mug, stir together maple syrup and coconut oil until combined.
Add the lemon juice, almond milk, and lemon zest and stir to combine. The mixture will likely become a little separated, but if it starts to look chunky and curdled, put it in the microwave for a few seconds until the coconut oil melts again.
Add the flour and baking soda, stirring quickly until just combined.
Microwave for 70 seconds or until the top is no longer wet and the cake feels springy to the touch. Let cool a few minutes before eating or glazing.
In a small bowl, add lemon juice to powdered sugar a few drops at a time until the desired consistency is reached. I like it just thin enough to drizzle off the spoon.
Drizzle over the lemon mug cake or just pour it all over the top and enjoy.
Tips for customizing lemon mug cake
Skip the glaze and top with sprinkles, a drizzle of honey, or a dusting of powdered sugar
Add a few raspberries or blueberries with the flour
Try it with other citrus such as lime, grapefruit, or orange
Top with honey sweetened Greek yogurt for a filling breakfast