1. Pour some kosher salt into a small dish. Rub 1 lime slice over half the rim of glass. Dip rim of glass into salt.
2. Combine tequila, agave syrup, Cointreau and juice in a cocktail shaker; fill with ice and shake well. Strain into prepared glass. Garnish with second lime slice.
3. Drizzle grenadine to give the drama of fireworks in your glass.