Focaccia Barese al Pomodoro e Olive (Homemade Italian Focaccia with Tomatoes and Olives)

Place potato into a large pot and cover with salted water; bring to a boil. Reduce heat to medium-low and simmer until tender, about 20 minutes. Drain and rinse under cold running water.

Peel potato; mash in a large bowl with a fork. Pour in flour and mix well with your fingertips. Rub together until mixture is even and free of lumps.

Combine 1 cup water, yeast, and sugar in a bowl. Mix well and let stand until frothy, about 5 minutes. Stir in 5 tablespoons olive oil.