Begin by preparing your vegetables - wash and cut the cauliflower into florets and then into bite-sized pieces; peel and quarter the onion, and peel the garlic cloves. Also, peel and dice the potatoes, setting everything up for a seamless cooking process.
Preheat your oven to 425°F (220°C). Place the cauliflower florets, quartered onion, and whole peeled garlic cloves on a baking sheet lined with parchment paper. Season with salt and pepper, and toss to ensure even coating.
Roast the vegetables for 20-25 minutes (tossing halfway) or until the cauliflower is tender and slightly browned and the onion and garlic are soft. Remove some florets for garnish after they are roasted (optional).
While the vegetables are roasting, place the diced potatoes in a large pot. Add the vegetable broth, coconut aminos, and salt, bring to a boil, then reduce heat, cover, and simmer for about 15-20 minutes, until the potatoes are soft.
Add the roasted cauliflower (except the reserved roasted florets for garnish), onion, and garlic to the pot with the potatoes*. Stir in ground cumin, ground nutmeg, and additional salt and pepper to taste. Simmer for 5 to 10 minutes or until all the vegetables are very soft.
Puree the soup using an immersion blender until smooth and creamy. Alternatively, carefully transfer the soup to a blender (that is safe for hot food) in batches and blend until smooth.
Return the soup to the pot (if using a blender), stir in the almond milk, and heat over medium heat until warm. Before serving, adjust the seasoning if necessary, and stir in the lemon juice.
Serve the soup hot, garnished with the reserved roasted cauliflower florets and fresh parsley or chives if desired.