Sift first 3 ingredients over a large mixing bowl. Add 1/2 cup of chilled club soda and mix with chop sticks or fork. Add the rest of the club soda and mix. Be careful not to over mix. The lumps give the tempura batter its unique texture. Over moderately high heat fill a deep pan or wok with about 3 inches of vegetable oil. Add vegetables sparingly to the batter making sure they are covered. Place vegetables 1 at a time in the oil and fry until batter has turned golden brown about 1 minute. Repeat until all vegetables have been cooked. Serve with soy sauce for dipping.
Recipe courtesy of Danny Boome, 2008