Scatter tajin onto a plate. Use a lime half to wet the rim of a glass.
Dip the rim of the glass into the tajin until the edge is covered.
Place frozen diced mango in a blender. Add lime juice, ice, orange liqueur, tequila if using, agave nectar, and mango nectar to the blender, and blend on medium-high speed until puréed. Blend until mango mixture reaches the desired consistency.
Drizzle 1 to 2 tablespoons of chamoy onto the sides of each margarita glass in a decorative swirl.
Garnish each glass with a tamarind candy straw, if using, and a spoon. Serve immediately.
Peel and dice mangos and freeze for 6 hours or overnight or use packaged frozen mango chunks.
Fresh lime juice is a MUST in this recipe.
If you do not have mango nectar, feel free to substitute with fresh orange juice, pineapple juice, homemade simple syrup, or even water.
If you don’t have agave nectar feel free to substitute with honey, maple syrup, or sugar.
If you are going to use water instead of mango nectar, I would recommend adding extra sweetener.