Using a paring knife, pierce the potato several times. Place on a plate and microwave on high until tender, about 8 minutes. Meanwhile, crumbling it with a spoon, brown the turkey in a nonstick skillet over medium-high heat for 8 minutes. Stir in the onion, tomatoes, beans, chili powder, and pepper and simmer for 7 minutes. Serve with the baked potato and butter.