How to Make It
Preheat the oven to 375°. Pull the outer leaves off the artichokes until you reach the yellow inner leaves. With a small, sharp knife, trim the stems and any dark green spots from the artichoke bottoms. Rub with the lemon. Slice the artichokes lengthwise 1/8 inch thick and place in a bowl; squeeze the lemon half over them and toss to coat with juice.
Blanch the fava beans in a medium saucepan of boiling water for about 15 seconds to loosen their skins. Drain and let cool, then peel the fava beans.
In a large, deep skillet, warm the 6 tablespoons of olive oil. Add the garlic and shallot and cook over moderate heat until fragrant, about 3 minutes. Stir in the artichokes until coated with oil and spread in an even layer. Cover with a round of parchment paper an inch larger than the skillet, pressing it directly over the artichokes. Cover the skillet with a lid and cook over moderately low heat until the artichokes are barely tender, about 3 minutes. Add the asparagus, cover with the parchment and lid and cook for about 3 minutes.
Repeat with the scallions, peas and fava beans, adding them at approximate 3-minute intervals and adjusting the heat so the vegetables sweat but do not brown. Season with salt, stir in the herbs and remove the skillet from the heat.
Put the bread slices on a baking sheet, lightly brush both sides with olive oil and bake until golden brown, about 4 minutes per side. Set the toasts on plates, spoon the vegetables on top and serve.