Heat the margarine and add the leeks. Saute on medium heat for about 10-12 minutes, or until softened and browning slightly.
Add the broccoli, milk, garlic and Mother Mix. Bring to a boil, then reduce heat and simmer, covered. After 10 minutes, check to see if the broccoli is fork tender. If not, cook until it is.
Add the lemon juice and zest.
Add salt and pepper to taste.
If you want to blend part or all of the soup
Use an immersion blender, or transfer to a countertop blender. It's a good idea to let the soup cool down a bit before blending it. Hot soup exploding out of the blender can be very dangerous.
Notes
Storage and Reheating
Store in a well-sealed container in the fridge for 2-3 days. Reheat over low heat. Add plant-milk as necessary to thin it out.