Finely mince the onion, shallots and garlic in a food chopper or with a sharp knife (see step-by-step pictures in post above).
Heat some olive oil in a Dutch oven or a large heavy pot. Fry the cloves, peppercorns, and juniper berries (if using) for 2 minutes over medium-high heat. Skip this step if using a bouquet garni.
Add the minced onion, shallots and garlic to the pot. Sauté for 3 minutes until translucent.
Add the cauliflower rice and sauté for 3 minutes over medium-high heat without stirring. Then, give it a good stir and cook for 2 more minutes.
Pour in the strained tomatoes. Add the tomato paste, tamari, sugar, bouillon powder, a pinch of salt and the bay leaf (or bouquet garni).
Cover with a lid and simmer for 15 minutes over medium heat (or up to 1h over low-medium heat if time allows).
In the meantime, bring water to a boil. Cook the spaghetti according to package directions. Drain when cooked.
Serve the spaghettit with the cauliflower bolognese.