Remove the tough muscle at the side of each scallop. Reserve the muscles and set the scallops aside.
Heat the olive oil in a small saucepan over medium heat. Add the onion, fennel, and celery. Season with salt and pepper and cook, stirring occasionally, until the vegetables are tender but not browned, about 20 minutes. Reduce the heat to medium low. Add the scallop muscles and cook until they are firm, 2 to 3 minutes. Add the wine and simmer until the pan is almost dry, about 7 minutes. Add the stock and the herbs. Simmer until the stock has reduced by half. Strain the sauce through a fine sieve, then return it to the pan. Bring the sauce to a simmer over medium heat. Whisk in 1 tablespoon of the butter. Adjust the seasoning with salt and pepper and keep warm over very low heat.
Dry the scallops with paper towels. Heat a large skillet over medium-high heat. Add the peanut oil. Season the scallops with salt and pepper and add them to the skillet (work in batches if cooking all the scallops at once would crowd the pan). Cook the scallops without moving them until they are golden brown, 1 to 2 minutes, then flip them and add the remaining 2 tablespoons butter and the thyme. Baste with the foaming butter and cook until they are firm outside but just barely warm at the center, about 30 seconds more. Serve the scallops with a drizzle of the jus.