In a large pot or container, heat 4 liters of water to 124°F/51°C.
Dry the scallops with a paper towel and season both sides with salt and pepper.
In a sous vide bag, pack the scallops with the flat side facing up, along with 1 tablespoon butter and the garlic. Cook for 30 minutes.
Remove the scallops and soak up the excess moisture with a paper towel.
In a medium skillet, melt the remaining butter over high heat. Once it starts to foam, sear the scallops for 20 to 30 seconds per side. Then immediately remove the scallops from the skillet.
Finish the scallops with lemon peel and flaky salt. Serve with a sauce, such as green herb pesto.