To make Batter: In bowl, combine flour and baking soda. Gradually stir in beer and soy sauce, whisking just untl smooth. Hold at room temperature no longer than 1/2 hour. (Yield: 12 cups)
In deep fryer, heat oil to 375 degrees. Dip mushrooms into batter; fry about 4 minutes or until crisp and golden. Serve immediately.