Prep the limes: Wash and dry the limes thoroughly. Any moisture can cause spoilage.
Cut each lime into small bite-size pieces—either quarters and then crosswise slices, or eighths if the limes are large. Remove visible seeds for a cleaner taste.
Salt and soften: In a clean bowl, toss lime pieces with salt and turmeric. Transfer to a clean glass jar, cover, and let sit at room temperature for 24–48 hours.
Shake the jar once or twice a day to distribute the salt. This step softens the rinds and starts the curing process.
Toast whole spices: In a dry pan over low heat, toast mustard, fenugreek, and fennel seeds for 1–2 minutes until fragrant. Don’t let them burn—they should just release aroma.
Grind the spices: Cool, then grind the toasted seeds to a coarse powder using a spice grinder or mortar and pestle.
A bit of texture is nice.
Warm the oil and bloom aromatics: Heat the oil gently. If using mustard oil, heat until it just starts to smoke, then cool slightly to mellow its sharpness. Add asafoetida and stir for a few seconds.
Add spices and chili: Turn off the heat.
Stir in the ground spice mix and red chili powder. Let the mixture cool until warm, not hot.
Combine with limes: Pour the spiced oil over the salted lime pieces. Add sugar or jaggery if using, plus lime juice to loosen the mixture.
Stir well to coat all pieces evenly.
Adjust seasoning: Taste carefully. Add more salt for savoriness, chili for heat, or a pinch more sugar for balance. The flavors will deepen over time, so err on the side of slightly bold.
Cure the pickle: Pack into a clean, dry glass jar.
Press down to remove air pockets. Cover and leave at room temperature for 2–3 days to meld. Shake or stir daily with a clean, dry spoon.
Store: After curing, refrigerate.
The pickle tastes great on day three and even better after a week. It will keep for several weeks if handled with clean utensils.