How to Make It
Squeeze the juice of 1 lemon half into a bowl of cold water and drop the half into the bowl. Working with 1 artichoke at a time, snap off the tough outer leaves. Using a sharp knife, cut off the top half of the artichoke and peel the base and stem. Cut off the stem and drop it into the bowl. Using a melon baller or a spoon, scoop out the furry choke. Rub the artichoke bottom all over with the other lemon half, then quarter the artichoke and drop the artichoke into the lemon water. Repeat with the remaining artichokes.
Drain the artichokes and pat them dry. Heat 2 tablespoons of the olive oil in a large saucepan. Add the artichokes, garlic, leeks, celery and fennel and cook over moderate heat for 2 minutes, stirring occasionally. Add the water and a pinch of salt and bring to a boil. Cover the saucepan and simmer for 15 minutes. Add the green beans and simmer until all of the vegetables are tender, about 10 minutes longer.
Drain the vegetables and reserve their cooking liquid. Return the cooking liquid to the saucepan and boil over high heat until it is reduced to 2 cups, about 10 minutes. Remove from the heat.
Season the lamb with salt and pepper and dust with the pimentón. In a large, deep skillet, heat the remaining 2 tablespoons of olive oil until shimmering. Add the lamb and cook over moderate heat until lightly browned, about 3 minutes per side. Transfer to a plate. Add the flour to the skillet and cook over low heat, stirring, for 1 minute. Gradually whisk in the wine and reduced vegetable cooking liquid and simmer for 5 minutes, whisking frequently. Stir in the vegetables and lamb and simmer until heated through, 4 minutes; the lamb should still be pink in the center. Season with salt and pepper and serve.