Heat 1 tablespoon coconut oil in a cast-iron skillet over medium heat. Add the pineapple and sear until very dark on one side, 5 to 10 minutes; it should look almost burned. Flip and add the remaining coconut oil if the pan looks dry. Cook on the reverse side until darkly seared, 5 to 10 minutes. Remove the pineapple to a cutting board and let cool before cutting into medium dice.
Add the pineapple, tangerines, coconut, marshmallows, sour cream and orange extract to a nonreactive bowl. Fold to combine. Cover with plastic wrap and refrigerate for 1 to 3 hours, until completely cold!!! Serve garnished with mint.
Stale the marshmallows by setting them on a plate and leaving them on the counter overnight. Toast the coconut flakes on a baking sheet in a 350-degree oven for 10 to 12 minutes.