1. Preheat oven to 425 degrees F. Spray a 9-by-13-inch baking pan with vegetable cooking spray.
2. Prepare potatoes. Cut potatoes in half and place in a large resealableplastic bag with onion. In a small bowl, mix garlic, 3 Tbsp. oil, and 2 Tbsp. mustard. Add to the bag and mix to coat the potatoes.
3. Empty bag of potatoes into prepared pan, arranged in a single layer. Bake for 45 to 60 minutes or until potatoes are fork tender. While potatoes cook, cook the bacon in a large skillet over medium heat until crispy, about 20 to 25 minutes. Drain, set aside to cool slightly, then crumble.
4. Prepare the dressing. In a large bowl, whisk together the vinegar, 2 Tbsp. mustard, 1 Tbsp. oil, salt, and pepper.
5. When the potatoes are cooked through, add the spinach to the dressing, toss tocoat, then add the hot potatoes and mix gently to coat. Transfer to a serving dish and sprinkle crumbled bacon over the top. Serve immediately.
Source: Fresh Magazine March, April 2010