1. In stockpot or large heavy saucepan, heat olive oil over medium heat. Add onion; cook until lightly browned, about 10 minutes. Add garlic and cook another minute or two.
2. Add potatoes, salt, pepper, and enough water or broth to cover potatoes; heat to boiling over high heat. Reduce heat to low; cover and simmer until potatoes are tender, about 20 - 30 minutes.
3. Use a potato masher to smash the potatoes in the pot. Add more water if they seem too thick.
4. Stir in greens; simmer, uncovered, until tender, about 5 to 8 minutes.
This is a version of a portuguese soup. My five year old daughter helps by rolling up the kale/collard greens into tubes so I can slice them thinly. =)
We have this a lot in the winter....it is easy and hearty!