In large canning jar with tight-fitting lid, combine vodka, orange liqueur, cranberry juice, and lime juice. Shake to blend. Add a splash more lime and a tiny bit of agave syrup, if you wish. Refrigerate until ready to serve.

To serve, rub orange peel over rims of 8 martini glasses. Fill cocktail shaker with ice. Giving canning jar with spirits a good shake, pour 1/6 of mixture over ice cubes. Shake cocktail shaker for about 10 seconds, then strain into prepared martini glass. Repeat with remaining glasses. Garnish each with frozen cranberries, lime slices, and an orange twist, if you wish.