Preheat the oven to 400 degrees F. In a mixing bowl, toss the potatoes and garlic with a drizzle of olive oil. Toss well. Season with salt and pepper. Place on a baking sheet and roast for 15 minutes. Remove from the oven and cool completely. Using a mini food processor, combine the mayonnaise, mustard and lemon juice. Process until smooth. Season with salt and pepper. Add the cilantro and continue to process until incorporated. In a mixing bowl, toss the roasted potatoes and garlic, cilantro mayonnaise, sliced eggs, and red onions. Mix well. Season with salt and pepper. Cover with plastic wrap and refrigerate for 2 hours. Remove from the refrigerator and mix the salad. Reseason with salt and pepper if needed.