Asparagus tempura with garlic and herb sauce

Method

1. For the green herb and garlic sauce, whizz all the ingredients in a mini food processor or in a jug with a stick blender. Taste and season with salt and a little pepper, then spoon into one large or 4 small bowls and chill until needed.
2. For the tempura, heat the oil for deep-frying to 190°C (use the digital probe thermometer). Make the batter by sifting the flour, cornflour and a small pinch of salt into a mixing bowl. Scoop 3 tbsp into a small bowl. Quickly stir the soda water into the remainder, with a fork or chopsticks if you have some, until only just mixed in but still a bit lumpy, then sprinkle the reserved flour on top. This will create a few extra lumps in the batter as you dip, which helps give a light, crisp batter.
3. Cut or snap off the woody ends (and discard) from each asparagus spear, then cut the spears in half lengthways. Drop the spears into the batter, about 5 at a time, (don’t worry if one or two touch and stick together, but don’t let them all stick together in one lump). Lift them out using 2 forks, then quickly drop them into the hot oil. Deep-fry for 11⁄2 minutes until crisp and very lightly golden, then remove the spears with a slotted spoon and drain briefly on plenty of kitchen paper.
4. Pile the battered asparagus onto warm plates, sprinkle with the chopped herbs and serve straightaway, with the green herb and garlic sauce for dipping.