Preheat your oven to 425°F (220°C) to ensure it's hot and ready for roasting.

Slice the fennel, potatoes, and onion into uniform pieces. Place them on a parchment-lined baking sheet, and toss with olive oil, salt, and pepper.

Slide the baking sheet into the preheated oven and roast the vegetables for 30–40 minutes. Halfway through, toss them for even browning.

Once roasted, transfer the vegetables to a large pot. Pour in enough water or vegetable broth to just cover the veggies, followed by the almond milk.

Using an immersion blender, blend the mixture until smooth, adjusting the consistency with more almond milk or broth as needed.

Place the pureed soup back on the stove over medium-low heat and warm it through for about 5–8 minutes.

Ladle the soup into bowls and garnish with reserved roasted fennel pieces and a sprinkle of fresh cracked pepper.