"Similar to the more well known version made with chicken livers, but I've made some additions. This came about when a co-worker gave me about a dozen duck breasts and I had to find a way to use them up. The result was an appetizer that continues to be a favorite at dinner parties, and one that can be prepared well in advance of actual cooking.
If you are like some people who don't care for the gamey flavor of wild duck, I'm including a technique to soften or tame it. This can be made the day before your party and kept tightly covered in the fridge. Bring to room temperature before the final grilling."
Soak spinach in a bowl of salted water until absorbed, about 10 minutes. Drain and dry on paper towels.
Carve out the duck meat on a flat work surface with a sharp boning knife, starting along the side of the duck's breast bone to the ribs. Continue cutting outwards, staying as close to the rib cage as possible. Freeze and save the bones for soup. Cut the meat into roughly even cubes.
Lay bacon slices on a work surface. Place 2 spinach leaves, 1 cube of duck, and 1 water chestnut at 1 end of each slice, rolling it up and securing the ends of the rumaki with a toothpick. Sprinkle thyme on top.
Preheat grill for medium-high heat and lightly oil the grate.
Grill the rumaki until brown and crisp, turning occasionally, about 8 minutes.
Arrange the rumaki on top of the remaining spinach leaves on a serving platter.
Soften the gamey flavor of wild duck if you're using it by treating the meat with a mirepoix. Cut 1 onion, 2 ribs celery, and 2 carrots into matchstick-size pieces. Mix together in a bowl. Place half of the mirepoix in a glass casserole dish. Lay duck meat on top and cover with the remaining mirepoix. Let stand for at least 2 hours. Remove duck and continue with the recipe.