Trim your chicken breasts. Cover the outside with salt and pepper. Put them in a Pressure Cooker (Instant Pot is what I use) for 12 minutes on high pressure and allow a 10 minute natural release. You can also skip this step and use rotisseree chicken or any kind of pre-cooked chicken you have on hand.

Put the chicken, onion, and pickle relish in a food processor. Pulse until well incorporated. You don't want to puree the chicken here so just pulse until the chicken is finely ground, but still has shape.

Pour the chicken into a bowl and add the mayo, mustard and a dash of salt and pepper. Stir it together and taste for seasoning. Add more salt and pepper as needed. Serve on a croissant or a few slices of whole grain bread as shown. Store leftover chicken salad in the fridge for 3-4 days.