Place first 3 ingredients in medium bowl. Press firmly on solidswith muddler or back of wooden spoon until mashed. Mix intequila, lime juice, Simple Syrup , and Cointreau, then 1 cup ice.Stir to blend well. Strain into large glass measuring cup. Divideremaining ice between 2 tall glasses. Pour Margarita mixtureover. Garnish with watermelon skewers and mint sprigs.