Final answer:
The employee's desire and motivation to learn a new culture is the most critical ingredient for developing a global mindset during an international assignment.
Step-by-step explanation:
The most critical ingredient for an employee to develop a global mindset when going on an international assignment is the employee's desire and motivation to learn a new culture. While other factors like the length of the assignment, having a mentor, and fluency in the language are important, they are not as crucial as the underlying motivation of the employee. A motivated employee with a growth mindset is more likely to be open, adaptable, and proactive in overcoming challenges and learning from the new environment. A strong work ethic, respect for diversity, and the ability to communicate and collaborate effectively are also key components of cultural competence that contribute to success in a global workplace.