Final answer:
The 'chica flaca' cocktail is served with tequila, and the main ingredient is tequila, a spirit made from the blue agave plant.
Step-by-step explanation:
The question appears to be referring to an alcoholic beverage, specifically the type of tequila used in the cocktail known as 'chica flaca.'
The main ingredient in many tequila-based cocktails is tequila itself, which is a distilled spirit made from the blue agave plant primarily in the area surrounding the city of Tequila, Mexico.
Depending on the specific recipe for 'chica flaca,' additional ingredients may vary, but tequila is the core component.