Pour 1-inch vegetable oil into a large, deep skillet.
Place over medium-high heat and heat to 350 degrees F.
Prepare the tempura batter according to package instructions. Dip the asparagus in the batter, place in the skillet and fry until golden and crispy, about 2 minutes. Fry in batches.
In a bowl, combine the soy sauce, mirin, ginger, lemon juice and scallions.
Serve the asparagus with the dipping sauce on the side.
