Poach the chicken breast, just simmer it in a pan of water for 10 or 15 minutes. Try to do this in advance to give it time to cool down. When it’s cool enough to handle, just pull it apart with your hands into shreds, the size of which you find satisfactory.
The biggest pain in the arse about this recipe is turning the potatoes into shoestring fries. It requires a little more patience than I possess but I still do it because the skinny fries are what makes this a salpicão, otherwise it’s just another chicken salad. So peel the potatoes and take your time slicing them up into very skinny chips. I suppose there exists some kind of gadget that might do this tedious chore for you, but I have yet to discover it. Anyway, get that done and soak the chips in cold water to help remove some of their starch. Rinse them off and dry them with some kitchen paper or a clean kitchen towel.
This recipe is, of course, adaptable, so you can omit anything you don’t like and add anything you do, one recipe suggests mango, which I have yet to try but it sounds intriguing. I rarely use ham to be honest, but I had some I needed to use up, so in it went. Mix it up well and add the mayonnaise and season with salt and pepper to your own taste. You could use sour cream instead of (or mixed with) mayo, or low fat yogurt if you are concerned about calories.