1 - step 1 For the nuoc cham, whisk together all of the ingredients with 5 tbsp hot water in a small bowl.

2 - Set aside while you make the tempura.

3 - step 2 Whisk the cornflour, plain flour, sesame seeds (if using) and a large pinch of salt together.

4 - Fill a large, deep pan no more than a third full with the vegetable oil and heat until it reaches 180C or a cube of bread dropped in browns in 20 seconds.

5 - step 3 Quickly whisk the soda water into the flour mixture, being careful not to overmix, then dunk in the broccoli using tongs.