Wash and Prepare Lemons: Thoroughly wash the lemons and make tiny incisions to prevent them from bursting during boiling. Add water to a pot, bring to a boil, and boil the lemons for 20 minutes.
Cool and Saute: Let lemons cool to room temperature, cut in half, cube, and remove seeds. Heat grapeseed oil in a pan over medium heat with Kashmiri chili powder, cumin powder, turmeric powder, salt, sugar, and mustard seeds, until sizzling.
Sauté Lemons: Add cubed lemons and sauté on medium-high heat for 7-8 minutes. Let cool and transfer to a clean glass container. Enjoy immediately or refrigerate for added flavor.