Bring water to a boil in a pot. Cut the cauliflower into smaller pieces, add to the boiling water along with vegetable stock cube. Lower the heat, let it simmer for 10-20 minutes, depending on how big your cauliflower pieces are.
Meanwhile peel and rinse the shrimps.
When the cauliflower is soft turn off the heat and set aside while you start to prepare the bok choy.
Preheat a nonstick pan over medium heat with some olive oil.
Add the minced garlic and ginger and let it fry for one minute, or just until it starts to get golden brown and soft.
Add the bok choy and tamari and let it fry for 1-2 minutes, just until the bok choy has softened slightly. Add the sesame oil and stir together.
Turn off the heat and add the shrimps. Stir together.
Meanwhile drain the cauliflower and mix until smooth using a hand mixer.
Add dijon mustard and chili powder (if using), stir together.
Divide the cauliflower purée between two plates.
Top with fried bok choy, shrimps and sesame seeds on top.