Put the diced potatoes into a saucepan, cover with water and bring to a boil. Simmer for about 15 minutes until tender. Drain then put them back into the saucepan. Cover and keep warm.
Meanwhile, thinly slice or chop the onion and mince the garlic.
Heat a little oil in a frying pan and gently sauté the onion for about 8 minutes.
Add the paprika and garlic, if used, and stir for a minute.
By now the potatoes should be cooked.
Add half of the milk and the butter to the potatoes. Mash them with a potato masher then fold in the paprika-fried onion and its jus.
Season with salt and pepper, then add more milk, if you want it creamy. Stir well with a wooden spoon.
Serve warm.