Trim any roots off the greens and rinse very well. Fill a large stockpot with water and bring to a boil (I used an 8-quart stockpot and filled it with 5 and a half quarts of water).
When the water comes to a boil, add a generous pinch of salt and the greens. Submerge the greens completely and cook for 15-20 minutes, until they are fork-tender.
Drain the greens and dress with the olive oil, lemon juice, and salt to taste. If making ahead, refrigerate the greens after draining and save the dressing just before serving.
This can be served warm or at room temperature.