Place the potatoes in a large saucepan and cover with cold water. Cover, bring to a boil, and reduce the heat. Simmer until the potatoes are tender when pierced with a fork, 20 to 25 minutes. Do not overcook.
Combine the tomatoes, bell pepper, onion, chopped cilantro, jalapeño, oil, and salt to taste in a small bowl. Set aside at room temperature until ready to se