Make the spice paste by combining and stirring together the mustard, cumin, turmeric, vinegar, ginger, white pepper, cinnamon and salt.
Heat the oil in a large saute pan over high heat. Add the onion and fry for 15-20 minutes, until slightly charred, stirring occasionally.
Turn down the heat to medium-high and add the garlic. Stir, until fragrant (~30 seconds) then put in the spice paste and cook until fragrant (~30 seconds).
Add the meat and brown (~3 minutes), stirring occasionally.
Add the coconut milk and water to the pan, then cover.
Bring to a boil before lowering the heat to medium (the liquid should be at a steady simmer.)
Cook for 60 minutes, or until meat is tender, stirring occasionally.
Once lamb is finished, put cauliflower rice on a plate topped with vindaloo and blanched bok choy on the side. Serve immediately.