Place the red and Yukon potatoes in a saucepan with cold salted water. Make sure water covers potatoes. Bring to boil, after 10 minutes, add the yams. Return to boil and cook until tender, not mushy. Drain and set aside to cool.
In bowl, whisk together the mayo, mustard, onion and garlic powders, red pepper, salt and black pepper. When potatoes are cool, toss them in mayo mixture and stir to gently coat and set aside.
Heat an indoor grill over medium-high heat. Brush grill with olive oil.
Using tongs, place potatoes on hot grill and cook on all sides to make grill marks. This takes about 1-3 minutes per side. Handle gently as not to break them.
In a saute pan, cook bacon until crisp. Set aside to cool. Once cool, pour bacon and fat into a bowl with olive oil.
In another bowl, whisk together vinegar and mustard. Slowly drizzle the olive-oil-bacon mixture, whisking to emulsify.
Add the parsley, green onions and season to taste. Whisk to blend.
In a large bowl, place the vinaigrette. Take the potatoes off the grill and place in the bowl with dressing. Gently toss, taste for seasoning. Serve warm or cold.
Recipe by Geaux Ask Alice! at https://geauxaskalice.com/variety-grilled-potato-salad/