In a pot, pour enough water to cover the chicken breast. Bring water to a boil, reduce heat to a minimum, add some salt and put chicken in. Poach for 15-20 minutes. When done, reserve and cool down.
While chicken cooks, peel and cube potato and carrot. Boil water in a pot with a steamer insert (or equivalent kitchen tool). Add potatoes and steam for 10 minutes. Add carrot and steam for another 5 minutes.
Add corn kernels and peas and steam for another couple of minutes.
Reserve vegetables and let cool down.
Finely chop onion and place in a bowl, squeeze lime juice on it.
When chicken is at room temperature, chop with a knife or shred with a knife. Mix with onion, vegetables, mayonnaise, salt and pepper.