Possible Clues:

• Burrito portion?
• Churro ingredient?
• Burrito feature?
• Feature of a burro but not a donkey?
• Consonant sound common in Spanish
• Alveolar trill, as it's commonly known
• Ingredient in an authentic burrito
• Alveolar trill, as in Spanish speech
• Part of 'rico' or 'roja'