Heat up 1 tsp of oil in a small pan on medium heat.
When the oil is hot, add in the rai, hing, and jeeru and let them sputter for roughly 30 seconds (make sure they don't burn).
Take the pan off of heat and let the oil cool for about a minute.
Add in the limbdi while the oil is still warm and mix it around so it crisps up.
Drizzle the oil and spices over the sandwich and serve while hot!