Peel the potatoes and chop them up into small pieces. Fill a high pan with water and add a good dash of salt to it. Then place the pan over high heat and add the chopped potatoes to the water.

Cook the potatoes for about 20 minutes or until tender. In the meantime peel and slice the yellow onion and garlic cloves. Add them to a non-stick pan together with a tablespoon of the butter. Season with a little pepper and salt.

Place the pan over medium-high heat and cook the onion for 15 to 20 minutes until soft and golden brown. Then turn the heat a little lower if necessary. Keep an eye on it so the onion doesn't burn. Add a drop of water if necessary. Stir regularly. Pour in the balsamic vinegar in the end. Add extra pepper or salt to taste if necessary.

Cook for another 2 minutes and then take the onions off the heat. Drain the cooked potatoes well and add them back to the pan. Then season with a generous pinch of pepper and salt.

Mash the potatoes roughly using a fork. Add the warm milk.

Then add the rest of the butter as well.

Stir well. Add the browned balsamic onions to the potatoes.

Stir well again. Check the seasoning and add extra pepper or salt to taste if necessary. Transfer the mashed potatoes to a warm and large dish and serve hot.