In a large soup pot, heat the oil or water over medium heat. Add the onion, cover, and cook until softened, about 5 minutes.

Add the potato and stir in the broth. Season with salt and pepper, to taste.

Bring to a boil, then reduce the heat to low, add the broccoli and simmer, uncovered, until the vegetables are tender, about 15 minutes.

Use a slotted spoon to remove 1/2 cup of small broccoli florets and set aside.

Add the nutritional yeast, almond butter, lemon juice, and mustard to the soup. Use an immersion blender to puree the soup directly in the pot or transfer to a high-speed blender or food processor and puree, in batches if necessary, then return to the pot.

Stir in the almond milk, then taste and adjust the seasonings, if necessary. Reheat the soup over low heat until hot.

To serve, ladle soup into bowls, garnish with the reserved broccoli florets. Serve hot.