Heat the oven to 220 C / 425 F with a rack in the middle. Drain the artichokes, then rinse and drain both cans of beans. Pat the artichokes and beans dry with a clean kitchen towel, and halve any artichoke pieces bigger than 4 cm.
Toss the artichokes on a 33 x 46 cm / 13 x 18 inch sheet pan with 2 tbsp olive oil, the oregano, and 1/2 tsp salt. Spread them in a single layer and roast for 10 minutes. While they roast, toss 250 g of the beans (half) with 1 tbsp olive oil and the smoked paprika in a bowl.
Pull the pan out, push the artichokes to one side, and scatter the oiled beans into the gaps. Roast for 15 more minutes, until the artichoke edges are browned and the beans look dry and slightly wrinkled with a few split skins.
While the pan roasts, shake the lemon zest, lemon juice, 3 tbsp olive oil, Dijon, garlic, 1/4 tsp salt, and pepper in a jar. Toss the remaining 250 g beans, the tomatoes, and the red onion with 2 tbsp of the dressing and let them sit until the pan comes out.
Toss the arugula with 1 tbsp of the dressing and divide it among four bowls. Spoon the dressed beans, tomatoes, and onion on top, then add the roasted artichokes and beans. Finish with feta, parsley, and a drizzle of the remaining dressing. Serve within 15 minutes.