In a cocktail shaker filled with a few ice cubes pour 25ml tequila, 25ml melon liqueur (I used Melonade, a lovely spirit made in Provence from the fragrant yellow-fleshed Cavaillon melon), the juice of 1 lime, and 2tsp agave syrup. Shake and serve on the rocks with a float (splash) of Grand Marnier on top.

Serves 1.