Mix 6 tablespoons of olive oil, the garlic, salt, pepper and herbs. Add potatoes and toss. Spread out onto a baking sheet and bake for 55 minutes, stirring occasionally. When potatoes are golden brown remove the pan from the oven and let cool. When potatoes are cool, place them in a bowl and scrape the pan drippings into a measuring cup. Add enough oil to the drippings to measure 6 tablespoons of oil. Whisk the vinegar and mustard in a small bowl. Gradually add the oil and then mix in the shallots. Pour the dressing over the potatoes and combine. Season with salt and pepper, if needed. Add chopped basil. Let stand for 1 hour at room temperature. Serve.