Cut the sweet potato into bite-sized pieces and soak in water briefly. Drain and place in a microwave-safe container. Cover loosely with plastic wrap and microwave at 600W for 5 minutes.

Roughly chop the onion and soak in water briefly to reduce sharpness. Drain well. Drain the oil from the canned tuna.

In a bowl, combine all the ☆ condiments (mayonnaise, grated cheese, chicken stock powder, and black pepper).