Abstract: An infuser and a system for preparing an infused beverage in a drinking cup. The infuser comprises a hollow cylinder comprising a plurality of orifices, an inner cavity, an opening in a top surface, a filter element and a threaded bottom portion. The system comprises a container, the infuser and a drinking straw. The system can be used with “single-serve” ingredients to be infused, in particular based on yerba mate, coffee or tea.