2 ounces tequila1/2 ounce agave nectar1 ounce freshly squeezed grapefruit juice1/2 ounce freshly squeezed lime juice1/2 teaspoon grated fresh gingerPinch of cayenne pepperIce cubesGrapefruit wedges, for garnishFill a shaker with ice. Add the tequila, agave nectar, grapefruit juice, lime juice, ginger and cayenne pepper. Shake well. Strain into a Margarita glass over ice. Garnish with the grapefruit wedges and serve.