How to Make It
Bring 2 medium saucepans of water to a boil and prepare a large bowl of ice water. Add the cranberry beans, whole garlic cloves and thyme sprigs to one saucepan and simmer over moderate heat until the beans are tender, about 30 minutes. Drain the beans and discard the garlic and thyme. Wipe out the saucepan and return the beans to it.
Meanwhile, preheat the oven to 425°. Add the fava beans to the second saucepan of boiling water and cook for 5 minutes. Using a slotted spoon, transfer the favas to the ice water to cool.
Add the haricots verts to the boiling water and cook until crisp-tender, about 4 minutes. Using a slotted spoon, transfer the haricots verts to the ice water to cool. Add the sugar snaps to the boiling water and cook for 2 minutes. Drain and add them to the ice water. Drain all the beans and peas and pat dry; pop the favas out of their outer skins. Add the beans, sugar snaps and baby peas to the cranberry beans.
Wipe out the medium saucepan and melt the 2 tablespoons of butter. Add the shallots and minced garlic and cook over moderate heat, stirring occasionally, until softened. Add the wine and cook until nearly evaporated, about 10 minutes. Add the chicken stock and cook until reduced to 1/4 cup, about 6 minutes. Reduce the heat to moderately low and whisk in the cubes of cold butter, a few at a time, until a creamy sauce forms. Add 1 tablespoon of the lemon juice and season the sauce lightly with salt and pepper. Pour all but 1/4 cup of the butter sauce over the vegetables and keep warm.
Heat the oil in a very large ovenproof skillet. Pat the halibut dry and season with salt and pepper. Add the fillets to the skillet and cook over high heat until lightly browned, about 3 minutes. Transfer the skillet to the oven and cook until the halibut is almost opaque throughout, about 5 minutes. Carefully turn the fillets. Add the remaining butter sauce to the skillet with the remaining 2 tablespoons of lemon juice and the chopped thyme. Cook over moderate heat just until the sauce is bubbling and the fish is just cooked through. Transfer the halibut fillets to plates and spoon the lemon-butter sauce on top. Garnish with the microgreens and serve with the beans.