First, make the syrup:

Combine all syrup ingredients in a large saucepan. I toss the juice and the lemon halves right in. The rind adds a nice flavor and you'll be straining it all at the end anyway. Bring to boil and reduce to low simmer for 20 minutes. Remove from heat and allow to cool to room temperature before straining. Discard all solids and pour syrup into a jar. Place in refrigerator and allow to cool completely before proceeding with cocktail. 

To make the cocktail:

In a cocktail shaker or large mason jar combine all cocktail ingredients. Give it a good stir, swirl, or shake and pour into a glass or small jar with lots of ice. Garnish with rhubarb ribbon or spear and fresh lemon wedge if desired. Serve with a straw to really drive home those pink lemonade, summertime vibes.