Decorate the glasses with the Bloody Rim Drip: On a small plate, stir together the corn syrup and food coloring until well combined. Lightly dip the rims of two margarita or cocktail glasses into the syrup, then turn the glasses right side up and transfer to the refrigerator to harden while you make the cocktail.

Make the Blackberry Heart Skewers: Thread 4 blackberries onto each skewer, pressing them together so they resemble a heart shape. Set aside.

Make the Margaritas: Fill a cocktail shaker or beaker with ice. Add tequila, beet juice, lime juice, agave nectar and orange liqueur and shake or stir well until thoroughly chilled.

Remove the prepared glasses from the refrigerator and fill with fresh ice. Strain margaritas into glasses. Garnish with the Blackberry Heart Skewers and dehydrated orange slices, if using. Serve immediately.