Cook the onions in olive oil until soft, about 8 minutes.
Add the garlic, broccoli stalks, potatoes, rosemary, and salt. Cook for 10-15 minutes until everything is sticky and the potatoes have softened somewhat.
Add just enough water (or stock) to cover the ingredients by about 2cm (approximately 800ml) and bring to a boil.
Add the broccoli florets and simmer until the potatoes and broccoli are cooked through.
Remove from heat and blend with a stick blender.
Check the seasoning and add more salt if needed, along with plenty of black pepper.
Stir in the lemon juice and zest.
Serve with croutons or toast, lots of grated cheese, chili flakes, and a drizzle of olive oil.
