Heat olive oil in a large frying pan on a medium high heat.
Add the garlic (if using) and the greens and a splash of water. Cover and allow to cook for about 2 minutes.
Stir, add more water if the greens are starting to burn then recover and cook for another few minutes. Continue to cook and stir every few minutes until the greens are just wilted.
Remove from the heat. Taste and season with salt, pepper and a little lemon juice, if you like. Serve.