Add the olive oil to a large enameled dutch oven and warm over medium-high heat. Add the mushrooms and cook, stirring occasionally, for about 15 minutes or until the mushrooms are very well browned. (Don't skimp on this step!)
Add the garlic, kosher salt, and ground black pepper to the dutch oven, reduce the heat to medium, and let cook for about 1 minute, stirring constantly, until fragrant.
Next, add several large handfuls of power greens to the dutch oven. Stir with a spatula and let wilt slightly, then keep adding more greens until they all fit in the dutch oven.
Continue cooking and stirring until the greens are wilted but still bright green.
Turn off the heat, squeeze the fresh lemon juice over the top, drizzle with a little extra olive oil, and a sprinkle of Maldon sea salt. Serve right away!