Heat the oven to 220 C / 425 F with a rack in the middle. Slice the sausage into 1.5 cm coins, cut the peppers into 2.5 cm strips and the onion into 8 wedges. Rinse the beans, then pat them dry with a clean towel and set them aside.
Toss the sausage, peppers and onion with 2 tbsp olive oil, the smoked paprika, oregano and black pepper on a 33 x 46 cm / 13 x 18-inch rimmed sheet pan. Spread in one layer and roast for 15 minutes, until the sausage edges are browned and the onion starts to char.
Toss the dried beans with 1 tbsp olive oil and the red pepper flakes. Scatter them over the pan, stir once, and roast for 10 minutes, until the beans look dry with a few split edges and the sausage reaches 165 F / 74 C.
Toss the kale and sliced garlic with the last 1 tbsp olive oil in a 4-quart / 4 L bowl. Add to the pan and roast for 5 minutes, until the kale edges are crisp and darkened and the garlic is golden.
Zest the lemon over the hot pan, squeeze in the juice, and sprinkle the Parmesan on top. Toss, taste, and add salt only if needed. Serve hot straight from the pan.