Cook the bacon in a deep saute pan on medium-high heat until crisp, then set aside, leaving the fat in the pan. Alternatively, heat butter, ghee or olive oil over medium-high heat. Add onion and garlic and sauté until tender, about 5-6 minutes. Add lemon zest, red pepper flakes, and saute a minute or two, until fragrant.
Add the greens and cook until they begin to wilt.
Add the bone broth and bring to a boil, reduce the heat, cover and simmer. Let cook until the greens are tender, about 45 minutes. Uncover, add back the bacon bits, raise the heat to medium-high, and reduce the liquid slightly, 1 to 2 minutes. Add the lemon juice, and season with salt and pepper, to taste
Notes
I keep the stems in when using Swiss chard, it adds a nice crunch and a little color. Plus less waste! For low FODMAP, leave out the garlic and onion For vegetarian/vegan use vegetable stock For AIP leave out red pepper flakes