Hibiscus-Lemon Margarita

Combine flowers and tequila in a glass jar with a lid. Shake well. Let stand 1 hour or until tequila is strongly flavored with hibiscus. Strain over a pitcher; discard solids. Add agave, juice, and Grand Marnier. Stir to combine.

Combine sugar, cinnamon, and salt on a small plate. Lightly dampen rim of a rocks glass using lemon wedge; dip in sugar mixture to coat rim. Repeat procedure with 5 more glasses. Fill glasses with ice cubes. Divide tequila mixture evenly among glasses. Top each cocktail with about 1 1/2 ounces club soda.