Asparagus tempura with chervil vinaigrette

Ingredients

• Chervil vinaigrette
• 1 clove garlic, crushed
• 1/4 cup (60ml) white wine vinegar
• 1/4 cup (60ml) olive oil
• 1 tablespoon finely chopped fresh chervil
• 2 teaspoons dijon mustard
• 2 tablespoons caster (superfine) sugar
• 500 grams (1 pound) chilled asparagus
• 1/2 cup (90g) rice flour
• 1/2 cup (75g) plain (all-purpose) flour
• 1/2 teaspoon baking powder
• 1 egg
• 1 1/4 cup (310ml) chilled soda water
• vegetable oil, for deep-frying
• 50 grams (1½ ounces) mizuna