In a large stock pot heat the olive oil and saute the onion and 1 tsp salt for 5-7 minutes over low to medium heat.
Add the potatoes, broccoli, stock, 1 tsp salt and bring to a boil, reduce to a simmer.
Cook covered for 12-15 minutes or until broccoli and potatoes are fork tender.
Pour the ingredients along with the lemon juice into a blender and puree.
Serve garnished with yogurt, creme fraiche or sour cream and shaved parmesan if desired.
To Freeze: Allow to cool, place in appropriate container or ziploc bag, label, and freeze. When ready, place in pot and heat through under low to medium heat or defrost in fridge over night.