Step 1In a 3-quart soup pot or cast-iron casserole (with a lid that fits), heat 1 1/2 tablespoons of olive oil and cook the onions and garlic over medium-low heat until softened, about 10 minutes.
Step 2After the vegetables are soft, add the dried beans and water to cover, about 3 cups. Bring to a simmer over high heat, then reduce the heat to low and cover the pot with the lid, stirring occasionally. After 45 minutes, add the black pepper, 1 1/2 teaspoons kosher salt and additional water if necessary to keep the beans covered. Cover and continue to cook until the beans are soft, again stirring occasionally, another 45 minutes to 1 hour. When the beans are tender, remove from the heat and allow to cool slightly. This makes about 6 cups cooked beans.
Step 3While the beans are cooking, make the salsa verde. In a medium bowl, combine the chopped tomatillos, red onion, jalapenos, cilantro, 1 tablespoon olive oil, a pinch of kosher salt and the juice of 2 limes. Stir to combine and reserve. This makes about 2 cups salsa.
Step 4Place the remaining tablespoon of oil in a large skillet and heat over medium-high heat. Add the chopped dandelion greens to the pan with a pinch of salt and saute, stirring frequently, until the greens are wilted, about 2 to 3 minutes. Remove from the heat and set aside. 5. Heat the tortillas over an open flame or in a griddle or saute pan on high heat, turning them over so that both sides are hot and lightly toasted. Assemble the tacos by arranging the grilled tortillas on individual plates or on a platter. Place about one-third cup of beans onto each tortilla, top with about one-fourth cup wilted greens and salsa verde to taste. Squeeze a wedge of lime over each taco (or serve with lime wedges) and serve immediately.