Heat oil in a pan on medium, then add fennel, mustard, nigella, and fenugreek seeds & let them sizzle and become fragrant.
Add the optional ginger and green chilies , sauté for a minute until aromatic.
Tip in the cranberries and water, then stir so they’re coated in the spiced oil.
Add red chili powder, salt, and sugar or jaggery & mix well.
Let the mixture simmer on medium-low, stirring occasionally, until most berries have burst and the chutney thickens, about 10–12 minutes.
Lightly mash with the back of a spoon if you like it smoother, or I leave some cranberries whole for texture.
Taste and adjust: add more sugar if too tart, more chili for heat, or a splash of water if it gets too thick.
Cool completely, transfer to a clean jar, and refrigerate; it thickens more as it cools and stays good for a couple months if stored in an air tight container.