Step 1Heat the oil in a large skillet over medium-high heat for 2 to 3 minutes, until the oil's almost smoking (you will begin to smell the oil at that point). Reduce the heat to medium, add the sausages and cook, turning them often for even browning, for about 7 minutes, until they're golden all over but not cooked through. Move the sausages to the side of the skillet to continue to cook while you sear the radicchio.
Step 2Put a couple of radicchio leaves in the skillet in a single layer and cook them for about 45 seconds on each side, until they're seared and wilted slightly. Remove the leaves to a plate and cook the remaining leaves in the same way, adding a bit more oil to the pan if it's dry. While you sear the radicchio leaves, continue to cook and turn the sausages for 10 more minutes, until they're cooked through, and transfer them to a plate when they're done.
Step 3Add a bit more olive oil if necessary to coat the skillet. Add the onions, garlic and a pinch of kosher salt and saute for about 1 1/2 minutes, until the onions are soft and the garlic is soft and fragrant, stirring constantly so the garlic doesn't brown.
Step 4Reduce the heat to medium, add the beans and broth, and simmer them until the liquid is reduced by half, about 5 minutes. Stir in the oregano and season with kosher salt.
Step 5Arrange four radicchio leaves in a clover pattern on each of four plates. Spoon the beans over the radicchio, dividing them evenly, and drizzle them with the sauce left in the skillet.
Step 6Cut the sausages in half at an angle and place the two pieces of each sausage side by side on each plate. Drizzle the sausage and beans with the high-quality olive oil.