Heat the oil with the garlic in a heavy skillet over medium heat. Cook stirring occasionally, until the garlic is golden. Remove the garlic from the skillet with a slotted spoon and transfer to a paper towel.v
Add the butter to the oil in the skillet and heat over medium heat. Add the onions, salt and pepper and sauté, until the onions are translucent and starting to turn golden.
Add the beans and continue cooking stirring occasionally. Stir in both vinegars and season with salt and pepper to taste.
Transfer the beans to a serving dish and sprinkle with the garlic chips.