Wash and peel the potatoes. Cut them into slices that are 3/4 inch thick. Put them in a saucepan with enough water to cover the potatoes. Bring the water to a boil on medium heat. Cook the potatoes for 20 to 25 minutes until they’re soft. Drain the water. Put the potatoes in a medium bowl. Use a fork or potato masher to mash the potatoes. Mix in the thyme, salt and pepper.