Heat oil in a large pot.
Sauté onion, garlic, salt, and pepper for about 4 minutes.
Add vegetables and cook for another 5 to 7 minutes.
Add broth and milk, cover, and simmer for 25 to 30 minutes.
Blend until smooth, then stir in nutritional yeast and cayenne.
Finish with lemon or vinegar, and adjust seasoning to taste.
