Saltfor rimming the glasses (I like to use citrus salts)
Lime wedgesfor rimming the glasses
In a small saucepan, combine the water and sugar. Heat over high heat, stirring so that the sugar dissolves into the water. The mixture will go from milky white to clear. At this point, add the sliced habanero.
Allow the mixture to come to a rapid boil, and then immediately turn the heat down so it just simmers. Let it simmer for 10 minutes, and then remove from the heat. The syrup will reduce and thicken slightly, and will take on a slightly orange tint.
Allow the syrup to cool (about 30 minutes). Remove the pepper pieces and any stray floating seeds, and discard them.
Run a lime wedge along the lip of your glass and dip in salt to cover the rim. Combine the tequila, grapefruit juice, triple sec and simple syrup in a cocktail shaker. Shake to combine and strain into a salted margarita glass. Add ice cubes and serve.