Preheat the oven to 400F. Line a muffin pan with papers or spray with non-stick cooking spray.
In a large mixing bowl combine the flour, 3/4 cup sugar, baking powder, and salt. In another mixing bowl combine the buttermilk, oil, eggs, and zest of 1 lime. Beat well to combine.
Pour the wet mixture over the dry and add the cherries. Fold in with a rubber spatula just until combined.
Scoop the batter into muffin cups, dividing evenly.
In a small bowl combine the demerara sugar and zest of 1 lime. Sprinkle the unbaked muffin tops with this sugar-lime zest mixture.
Bake in preheated oven for about 20 minutes or until tester comes out clean.
To make ahead: Baked and cooled muffins can be stored in an ziptop freezer bag in the freezer. Thaw on the counter before serving. Refresh in a 350degree oven for 5 minutes, if preferred.Nutritional value is for 1 muffin.