Preheat oven to 350-degrees.
Place the bratwurst on a baking sheet and cook in a preheated oven for 35-40 minutes.
Remove the brats from the oven and allow to cool completely.
Once cooled, insert an extra long skewer into the brats at least half way up.
If needed dry the bratwurst on paper towels before battering.
Bring the oil to a temperature of 375-degrees in a long, tall saucepan (tall enough to fit a bratwurst, lengthwise).
In a large bowl, whisk the all-purpose flour, corn meal, sugar, baking powder, baking soda and salt.
Whisk the egg and the beer into the dry mixture until a thick and slightly lumpy batter forms.
Transfer the batter into a tall container.
One by one dip each skewered and dried bratwurst into the batter allowing some of the batter to drip off before transferring it to the hot oil.
Carefully (but still holding the wooden skewer) lower the battered brat into the hot oil, making sure not to let the brat touch the sides or bottom of the pan, but making sure the entire brat is submersed in the oil.
Hold the skewer until the brat is golden brown.
Remove the brat to paper towels to drain and continue the process with the remaining brats and batter.
Serve hot with yellow mustard, and enjoy!