In a coffee/spice grinder, grind melon seeds, poppy seeds, green chile and 1/2 cup water to form a paste.
In a deep skillet, heat oil. Add cauliflower and saute until well browned, about 10 minutes. Add cashews and fry another 2-3 minutes. Remove cauliflower and cashews from pan.
Add mustard oil to skillet. After 1 minute, add red chiles and all whole spices. Fry for 1 minute. Add onion and saute until golden brown. Add ginger paste and garlic paste. Fry for 1 minute.
Add poppy seed paste and simmer on low heat for 5 minutes.
In a small bowl, whisk together the yogurt and besan. Add 1 cup water and mix well. Add to skillet with sugar and salt. Add cauliflower and cashews. Stir to combine and simmer on medium low heat for 10 minutes.
Add garam masala and ghee. Cook for 1 more minute.