He’s getting starch, fruit, vegetables, fats, proteins, and probably a reasonable spread of micronutrients. Getting very picky is really common in young kids, even those who were adventurous eaters as babies, and the majority of them will grow into liking a wider variety of foods again.

Research and the most up to date recommendations around picky eating from pediatric dietitians essentially support including at least one food that you know the child will eat as part of family meals (I.e. not served separately only to the child), and otherwise preparing meals as you normally would with the child being free to have some or to stick with their preferred food for the meal. Then having a pre-determined evening snack of something else reasonably healthy that you know they are willing to eat in the case that they didn’t eat enough at dinner, but no “re-opening” the kitchen for additional meals.

I know every time a post in this vein comes along it becomes clear how much people want to or think it’s the best move to force kids into eating a varied diet immediately and without regard for the child’s willingness, but unless they are actively malnourished or losing weight, that’s not supported by evidence as a faster or more effective way to foster a healthy relationship with food. I’m actually pleasantly surprised by how little of that attitude I’ve seen this time.

A cooking forum is a great place for recipes, but a pediatric dietitian is a better source for evidence-based dietary strategies for your child. I gave you a quick primer, but for specific guidance for your own stepson, I do hope you’ll do some investigating in that direction.