Preheat the oven to somewhere around 400 degrees.
Toss the diced potatoes in a bowl along with 2 tablespoons of oil and some salt and pepper, before placing them on a baking sheet.
Roast them for 30 to 40 minutes at most, flipping them over halfway through, when they become tender.
Remove them and let them cool for a while in a bowl, before adding the minced celery.
While they’re cooling, whisk together the remaining oil, lemon juice, yogurt and some salt and pepper. Taste it a bit to see if you need more or less of some ingredients.
After you’re done with that, pour it over the potatoes and toss them to get the completely coated in it.
Garnish them with some minced mint and serve to 4 or 5 people at most.