Combine the raisins and capers in a small bowl, add the Madeira and stock; soak for about 30 minutes.
Heat a small heavy skillet over medium-high heat until very hot. Add the foie gras; sauté until browned and cooked through, about 2 minutes per side. Transfer to two small plates and keep warm.
Pour off any fat in the skillet, and add the raisin/caper