1. Bring a pot of well salted water to a boil and prepare an ice bath. Remove the outer shell of each fava bean. Blanch the fava beans in the boiling water until they are bright green and tender, about 4 to 5 minutes. Remove the beans and plunge them into the ice bath. When cool, drain and dry on paper towels.
2. In a small sauce pot, cook the onion, garlic, thyme, pinch of salt, fresh pepper and olive oil over medium heat until the onion begins to wilt, about 5 minutes. Add the chicken stock.
3. Peel and dice the potato and add it to the pot. Cook, uncovered, until the potato is completely tender, about 20 minutes. Add a splash of chicken stock as needed to prevent the mixture from drying out.
4. If using fresh thyme, remove it now. Puree the potato mixture in a blender or food processor. Add the fava beans and puree. Add chicken stock by the tablespoon until the consistency is pourable. Taste and adjust the seasoning with salt and pepper. Keep warm.
For the scallops:
1. Season the scallops with salt and pepper.
2. Add the oil to a sauté pan and heat over high heat.
3. Add the scallops to the hot pan and sear for about 2 minutes on each side.
4. To serve, place 1/4 cup of the fava bean puree in the center of a warmed plate and top with the scallops.