Preheat BBQ to 350°F (180°C).
Wash and dry potatoes, then cut into quarters. Place into a large pot of cold, salted water and bring to a boil. Reduce heat and cook potatoes until fork tender, about 20-25 minutes. Remove from heat, drain and transfer to a bowl. Add oil, salt and pepper. Mix and set aside.
Lightly brush corn with melted butter and place directly on the grill. Allow to sit for 3-4 minutes per side and flip until corn is charred on all sides. While corn is cooking, grill potatoes for 4-5 minutes. Remove corn and potatoes from BBQ.
Shave kernels off cob. Combine mango salsa ingredients and place in a medium bowl with the potatoes and corn kernels. Mix gently. Enjoy!