Preheat the oven to 450°F. Line a rimmed baking sheet pan with foil.
In a large bowl, coat the potatoes with 2 tablespoons of olive oil and place on the prepared pan. Roast the potatoes for 20 to 25 minutes, stirring occasionally, or until they are tender and golden. Remove from the oven and let cool.
In a small bowl, mix the basil, lemon juice, Dijon, garlic, salt and pepper. Whisk in 2/3 cup olive oil in a slow, steady stream. You may or may not wish to use all of the olive oil.
Place the roasted potatoes and onion in a large bowl. Gently toss with the dressing. Sprinkle with Parmesan cheese and crumbled bacon.
Notes
*If you are preparing this recipe as GLUTEN-FREE, just be sure to use brands of Dijon and bacon that are known to be GF.