Making the lime pickles is quite a time-consuming process, so let's make a big batch while we're at it.
for the lime pickles:
2 pounds limes, cut into 8 pieces
3/4 cup kosher salt
1/2 cup chili powder
40 garlic cloves, peeled and smashed
2/3 cup vegetable oil
1/4 cup white cumin seeds
3 tablespoons black mustard seeds
1/2 teaspoon asafoetida (optional)
for the onion bhajis:
canola oil, for frying
3 pounds white onions, thinly sliced (about 5)
1/2 cup wheat flour
1/2 cup tempura flour
3 tablespoons finely chopped cilantro, plus more for garnish
3 tablespoons grated ginger
1 tablespoon turmeric
2 1/2 teaspoons kosher salt, plus more to taste
2 green chilies, minced
1 cup mayonnaise
1/2 cup lime pickle
1. Make the lime pickle: In a large bowl, toss the limes, salt, chili powder, and garlic, pressing down on them as you do. Place in a steamer and steam until soft, about 20 minutes.
2. Transfer to a glass bowl and cover with a towel. Place in a warm place for 2 days, mixing every 8 hours.
3. After 2 days, heat the oil over medium-high until a thermometer reaches 375°F|190°C. Add in the cumin, mustard, and asafoetida and cook until the seeds begin to pop, about 30 seconds. Pour the mixture over the limes and stir well. Cover with a towel and leave for another 2 days, stirring every 8 hours.
4. Transfer the limes to a food processor and process until chunky. Transfer to a sterilized container and let sit in a cool place for at least 2 weeks before using.
5. Make the onion bhajis: Heat 3-inches of oil in a large saucepan until a deep-fry thermometer reaches 325°F|160°C.
6. In a large bowl, combine the flours, cilantro, ginger, turmeric, salt, chilies, and 1 1/2 cups|350 ml water until smooth. Add the onions and mix to coat.
7. Working in batches and using a 1/4 cup measure or just a small handful, form the onions into a rough ball and place in the oil. Cook, turning as needed, untildark golden brown, 3 to 4 minutes. Using a slotted spoon, transfer the bhajis to a paper towel-lined plate and season with salt.
8. Mix the mayonnaise and the lime pickle in a small bowl. Serve with the onion bhajis and garnish with the cilantro.