How to Make It
In a bowl, mix the garlic and 1 tablespoon each of the miso and the oil. Set the duck in a glass baking dish and rub all over with the miso mixture; refrigerate overnight.
In a blender, process 1 cup of the almonds, the water, honey, sambal oelek, 2 tablespoons of the oil and the remaining 2 tablespoons of miso until smooth. Press the miso butter through a strainer into a small bowl.
Preheat the oven to 450°. Rinse the marinade off the duck; pat dry. Lightly season the skin with salt. Heat a large, ovenproof skillet. Add the duck, skin side down, and cook over high heat until some fat is rendered, about 1 minute. Reduce the heat to moderate and cook until the skin is golden, about 7 minutes. Transfer the skillet to the oven and roast for about 10 minutes, until the duck is slightly firm to the touch and the meat is medium. Transfer to a cutting board and let rest for 10 minutes.
Coarsely chop the remaining 2 tablespoons of almonds. Spoon the miso-almond butter onto plates. Thinly slice the duck breasts crosswise and arrange the slices on the almond butter. Garnish with the chopped almonds and serve.