Preheat your oven to 350°F (175°C).

In a large mixing bowl, combine the diced mango, lemon juice, and sugar. Toss until well-coated. Spread evenly in a prepared baking dish.

In another bowl, whisk together flour, oats, brown sugar, cinnamon, and salt. Blend in cold butter until mixture resembles coarse crumbs.

Sprinkle crumble topping over the mango filling evenly.

Bake in the preheated oven for 35-40 minutes until topping is golden brown and filling is bubbling.

Let cool for a few minutes before serving warm, optionally with ice cream.