Mangonada

5 large ripe mangoes (about 15 ounces each), peeled, pitted and cut into 1/2-inch pieces (about 8 cups), or 2 1/2 pounds frozen mango, defrosted
¼ cup granulated sugar, or to taste
¼ cup fresh lime juice (from 2 fresh limes)
1 ½ cups cold water, or as needed
¾ cup silver tequila or rum (optional)
¾ to 1 cup chamoy
Tajín, to taste
4 tamarind candy straws (optional)

Place 5 cups mango in a blender, reserving the remaining mango. Add the sugar, lime juice and 3/4 cup cold water to the blender, and blend on medium-high speed until puréed. Blend in tequila or rum, if using. Blend in additional water, adding 1/4 cup at a time, until mango mixture reaches the desired consistency.
Chill mango mixture, covered, in refrigerator until ready to serve. For a colder mangonada, transfer mixture to the freezer until it reaches the consistency of a slushy.
To serve, pour or scoop about 1/2 cup of mango mixture into each of four 16-ounce glasses. Add about 1/3 cup reserved mango to each glass, followed by 1 1/2 to 2 tablespoons chamoy and a generous sprinkle of Tajín. Repeat with the remaining mango mixture, mango pieces, chamoy and a final sprinkling of Tajín on top. Garnish each glass with a tamarind candy straw, if using, and a spoon. Serve immediately.