Start with a small amount of thoroughly cooked, hard-boiled egg yolk. To improve the texture and flavor, mash the yolk and mix it with a little breast milk or formula, which makes it less chalky and more palatable. If your baby rejects the initial taste, try incorporating it into different forms like steamed omelets or pancakes, or mix it with avocado. Always introduce it during the day to monitor for any signs of an allergic reaction.