Preheat the oven to 425.

Add the cauliflower and potatoes to a sheet pan, add the thyme, then drizzle with olive oil, salt and pepper, and toss to combine.

Add the onion and garlic, drizzle the tops with olive oil, then turn the onion and garlic face down.

Place the sheet pan in the oven for 50-55 minutes, flipping the cauliflower and potatoes halfway, until tender.

While the cauliflower roasts, add the scallions, rosemary, pistachios, salt and pepper to a small bowl.

Heat the avocado oil over medium heat until sizzling, then pour the hot oil over the bowl and let it sit to develop flavor.

Remove the sheet pan from the oven, squeeze out the roasted garlic, remove the outer layers of the onion, and discard the shells and thyme stems.

Add the cauliflower, potatoes, onion and garlic to a high speed blender with the broth, cashews, tamari, salt and pepper.

Blend until smooth.

Serve the soup topped with the pistachio-rosemary oil, fresh thyme, cracked pepper and lemon juice.