Put half the sugar and mint leaves into a cocktail shaker. Muddle together until the sugar has dissolved. Add the mango chunks and muddle again until the mango resembles a puree.
Add the rum. At this point you could strain the cocktail but I like it with the mango and mint leaves left in it. Pour over ice in the glass you're using to serve the cocktail. Top up with soda water.
To Make the Tacos and Slaw
Marinate the fish in a tablespoon of olive oil, the lime and orange juice, garlic, smoked paprika, cumin and a sprinkling of salt and pepper for about 15 minutes. Heat the remaining tablespoon of oil over a high heat and cook the fish for about 3-5 minutes on each side until cooked through. Place on a board and flake.
Place the cabbage, chilli, carrot, coriander, vinegar, syrup and a sprinkling of salt and pepper into a large bowl. Mix thoroughly. Serve the tortillas with the flaked fish and slaw and a mojito on the side!