Preheat an oven to 400 F and place baking sheet in the oven to preheat with the oven. Chop cauliflower head into smaller florets and drizzle 2 ½ T olive oil on top and toss together. Remove hot baking sheet from oven and place cauliflower on top sprinkling over 1 teaspoon kosher salt. Roast for 25-30 minutes.
In the meantime, smash garlic cloves and slice the onion. Add 2 teaspoons of olive oil to a saucepan to heat, then add in garlic, fennel seeds and sliced onion. Add a pinch of salt. Cook for 2-3 minutes until nicely browned.
Add in 2 T apple cider vinegar to deglaze pan. Add in stock, tumeric, ¼ teaspoons of salt and pepper. Simmer for 5 minutes then turn off the heat and add the whole milk and water.
Once cauliflower is roasted and soft with good browning, place in a blender with half of the turmeric liquid. Blend and add the other half. It shouldn’t need it, but if the soup is too thick add more water to make sure it is a drinkable consistency. Adjust seasonings if needed, adding more salt, pepper or apple cider vinegar.
Top each soup with sour cream. Add a little water to the sour cream before dolloping into the soup if it’s thick. Top with roasted pepitas and and a few red pepper flakes!