Cut off the leaves and trim the bottom stem and core. Dip in salted water to clean thoroughly.
In a small mixing bowl, combine all ingredients for the marinade. Mix well.
Spread marinade all over the cauliflower. Wrap in foil and refrigerate upside down for 15 mins-2 hrs.
Melt butter and add chopped onion and garlic. Saute. Add vegetable stock and garam masala.
Pressure cook on high for 2 minutes, wait 5 minutes, then manually release the pressure.
Transfer the cauliflower to an oven-safe dish and broil on high for 5-7 minutes to brown.
Turn on Saute. Stir in cornstarch in the heavy whipping cream, and whisk until smooth. Simmer to thicken.
Slice and serve with gravy!