Peel, wash and chop the potatoes in 2 halves. Boil them in salted water for 10 min.
Drain them well and arrange in an oven dish, in which you've melted the butter and a little olive oil. The potatoes need to be all in 1 row.
Bake at 374°F (190 °C) for 20 min. Combine the pressed garlic in a bowl with the vinegar and a little olive oil.
Take the potatoes out and with a hand blender, mash them to the bottom of an oven dish.
Flip them over and put a little of the garlic and vinegar in each. Sprinkle with the spices. Return to the oven for another 10-15 min.