Classic Tempura Batter

Fill a large, heavy-bottomed pot 1/3 to 1/2 full with vegetable oil. Heat oil over medium heat until a candy thermometer reads 375 °.  Meanwhile, make tempura batter: in a large bowl, whisk to combine flour and cornstarch. Measure beer or seltzer into a liquid measuring cup, then stir in egg. Add liquid ingredients to dry ingredients and stir until just combined. (Some pockets of dry flour are OK!) Add chopped vegetables and toss to coat. Transfer coated vegetables to the hot oil 2 to 3 pieces at a time, allowing excess batter to drip off before lowering into oil. Fry, turning frequently, until vegetables are lightly golden, 1 to 2 minutes. Remove to a paper-towel lined plate and season with salt immediately. Continue frying in batches until all vegetables are cooked. For sauce: in a small bowl, whisk together mayo, hot sauce, and garlic. Serve with tempura vegetables.