Add the shallots to a mixing bowl and sprinkle over the salt, stirring well to mix. Set aside for a few minutes to allow the salt to slightly soften the shallots.
Mix up the dip by adding the yogurt, mint, garlic and salt and pepper to a small bowl, stirring well to mix. Set aside.
Add the flour, chilli, nigella seeds and turmeric to the shallots, stirring well to combine. Stir through just enough water to bring the mixture together so a thick batter forms around the shallots, about 200ml. Set aside to rest whilst you heat up the oil.
Pour enough vegetable oil into a large deep saucepan so that it forms a 4-5cm layer. Turn on the heat and bring the oil up to 180°C, using a meat or jam thermometer to measure the temperature. If you don’t have a thermometer, drop in a little slice of the shallot, it should sizzle instantly. Alternatively, you can cook in a deep fat fryer, setting the dial to 180°C.
When the oil is hot enough, use a heaped teaspoon to scoop up the bhaji mix, then use another teaspoon to slide the mixture directly into the oil, working with care so the oil doesn’t splash. Repeat until you have added about 4-6 bhajis and fry for about 3-4 minutes until crisp and golden, carefully flipping over with a palate knife halfway through cooking. Scoop out with a slotted spoon and drain on kitchen paper whilst you repeat with the rest of the mixture.
As soon as all the bhajis are cooked, serve with the bowl of minted yogurt.