Banh tom Ho Tay

Step 1: Stir 2 tbsp sugar into 6 tbsp warm water until dissolved, then add 3 tbsp fish sauce, 2 tbsp lime juice, 1 clove garlic and 1 red bird's eye chilli. Drop in 2 ⅞ oz kohlrabi or green papaya and leave it to soak while you cook.

Step 2: Put 14 oz sweet potato in a bowl of cold water and leave for 10 minutes, then drain and dry thoroughly in a clean tea towel.

Step 3: Snip the feelers and legs off 7 oz small raw shrimp with scissors, devein through the back shell with a cocktail stick, pat dry and toss with a pinch of ⅓ tsp salt.

Step 4: Whisk 2 ⅞ oz plain flour, 1 ⅜ oz rice flour, ½ tsp ground turmeric, ½ tsp baking powder, the rest of ⅔ tsp salt and 1 tsp sugar with ¾ cup cold water to a batter like single cream. Stir in 2 spring onions.

Step 5: Add the dried sweet potato to the batter and turn it with your hands until every strand is thinly coated. There should be no pool of loose batter at the bottom.

Step 6: Heat 4 ¼ cups vegetable oil in a wok or deep pan to 350°F, or until a strand of potato sizzles at once and floats. Keep it at medium-high.

Step 7: Pile about 3 tablespoons of the mixture onto a flat slotted spatula or a ladle, spread it into a loose 8 cm round and press one shrimp on top. Lower it into the oil and slide it off.

Step 8: Fry 3 or 4 fritters at a time for 3–4 minutes, turning once, until deep golden, crisp at the edges and the shrimp is pink and opaque. Common mistake: crowding the pan drops the oil temperature and the fritters turn greasy and soft, so give them room.

Step 9: Lift onto a rack over kitchen paper and repeat with the rest, letting the oil come back to heat between batches.

Step 10: Cut each fritter in half and serve hot with 1 soft lettuce leaves, 1 oz mixed herbs (perilla, mint, Vietnamese coriander) and the dipping sauce. Eat the shrimp shell and all, or peel it if you like.