In a blender, bring one chopped mango and 3/8 cups of finely grated ginger to a puree consistency.
Transfer to a medium size saucepan and add 2/3 cups agave syrup, 6 ounces of gin and 1 cup of water. Bring to a boil on medium to high heat. Reduce heat to medium and simmer until a light syrup forms.
Strain syrup into a large measuring cup. Add 2 squeezed limes and let cool. Pour about 1/3 of syrup into an ice filled glass. Fill with tonic water and garnish with sprigs of mint and lime wedges.