Broccoli Cauliflower Soup

I was hoping this would be a pretty light green like my Cucumber Radish Soup, but I guess that wouldn't really make sense with so much broccoli and yellowish broth. The taste of the broccoli kind of overpowered the cauliflower too so I'll have to try some cauliflower soup without the broccoli next time. I forgot to add the lemon juice to the soymilk when I made my soup but I'm pretty sure that would make it even better.

1 cup plain soy milk
juice of half a lemon
1 tbs olive oil
1/2 onion, chopped
1 small head of broccoli
1 small head of cauliflower
2-3 cups veggie broth
2 tbs (vegan) butter
2 tbs flour
salt and pepper
green onions for garnish

Add the lemon juice to the soymilk and set aside. In a large pot, saute the onion in the oil until softened. Add the cauliflower and let it steam for a few minutes. Add broccoli and vegetable broth and bring to a boil. Simmer on low heat until veggies are soft enough to blend. Turn off the heat and blend the soup with an immersion blender. In a small saucepan, heat 2 tablespoons of margarine over medium heat until melted. Add the flour and whisk until combined. Gradually add the soy milk and whisk constantly until thickened and smooth. Add the soymilk mixture to the pot and stir to combine. Add salt and pepper and reheat until hot. Garnish with green onions.

Adapted from this recipe