In a small bowl, whisk together all ingredients except sliced scallions. Set aside.
Add enough oil to a large deep pot or dutch oven to come up the sides at least 3 inches. Attach a high heat thermometer to the side and heat oil to 350℉. Alternatively, you can use a deep fryer set to 350℉.
In a medium bowl whisk together water, flour, white wine, egg, cornstarch, baking soda and salt until smooth. Set aside while oil is heating and asparagus is prepped.
Trim woody ends from asparagus (about 2″). If some stalks are quite a bit thicker than others, thin by lightly peeling with a vegetable peeler to create more uniform stalks.
Once the oil is hot, dip individual asparagus spears into batter to evenly coat and tap off excess batter. Add to hot oil one at a time, cooking 6-8 per batch and cook for about 2 minutes per side depending on size. Remove with a slotted scoop to a paper towel lined tray and repeat with remaining asparagus.
Divided soy dipping sauce into small serving bowls and serve asparagus along side. Garnish with scallions and serve immediately.