Combine beans, oil, spices in pot. Cook until they've lost most of their water.
While thie is cooking, cut up the potatoes and onions, maybe 1/2" sized? Put them on a baking tray with oil, cook at 400F until they are browned but not burnt.
Add potatoes and onions to beans. Add olive oil and lemon juice, along with more of the salt/rosemary/fennel/garlic, to taste.