In a bowl whisk beer into flour until smooth and stir in salt. Make several shallow cuts across the inside curve of each shrimp and press shrimp gently ( to help prevent curling during the cooking). Peel sweet potato and cut cross-wise into 1/4-inch thick slices.
In a 3-quart saucepan, heat 2 inches of oil to 375 degrees. Working in batches of 3 or 4 pieces, dredge shrimp, sweet potato slices, bell pepper rings and asparagus spears in batter to coat completely, letting excess drip off and fry, turning, until golden, about 3 minutes. Transfer tempura as fried to brown paper with tongs to drain and season with salt. Serve with dipping sauce (recipe follows).
In a saucepan heat soy sauce, sugar and ginger until sugar dissolves, add rice vinegar and scallions.
Yield: about 1/2 cup
Recipe Courtesy of Gourmet Magazine