Step 1

Peel the mangoes and chop them into large pieces.

Step 2

Heat the oil over medium heat. Once hot, add the garlic and ginger and cook for 10 seconds, stirring constantly. Add all the spices (black nigella seeds, crushed red pepper flakes, coriander, salt, garam masala, cumin, cardamom, turmeric, mustard seed, cinnamon, cloves, and fenugreek), and then cook 20 seconds more, stirring constantly.

Step 3

Add the sugar, vinegar, water, and mangoes. Bring to a simmer, and then cover the pot and boil until the mango is soft and the chutney is thickened (remember it will thicken more as it cools), about 20 to 25 minutes, stirring occasionally.

Step 4

Cool to room temperature, and use or cover and store refrigerated.