@Truman If your husband enjoys some Thai dishes, I think you’re a long way along from the Midwest palate already! (And if Mexican flavors are acceptable, simple Indian food is not that far.)
Your description of your son reminds me of my younger nephew. (He won’t eat tomato sauce over pasta, but will eat almost exactly the same sauce with paneer, go figure.)
If I was going to venture down this path, I’d eschew most restaurant copycat food in favor of simpler home flavors.
I’d suggest starting with dal / lentils, roasted meat and veg with an indian flavor tweak, kheema / ground meat, and a light coconut curry that’s reminiscent of Thai.
I roast cauliflower with spices quite often (ground cumin, or garam masala, chaat masala, garlic and onion powders). Ditto squashes and root veg like carrots and parsnips — I love them tossed with cumin and garlic, or garam masala, roasted till slightly charred. Leftovers lend themselves well to purée soups (finish with a bit of milk or cream or coconut milk if you like, to soften the spice).
The same can be done with chicken or meat or fish — a light spice rub, a bit of ginger and/or garlic, yogurt if you want to make milder (or tenderize), then cook as you normally would.
Kheema is a close cousin of any other meat sauce: serve it as a rice bowl, as sloppy joes, over pasta, or as the base to shepherds pie. Simplify the spice profile if need be (swap whole spices for ground garam masala for eg). You can also add the same aromatics and/or spices to any meatball recipe and end up with basic but delicious home-style kababs / burgers.
Dal is an easy base — one of those dishes that are indian without always being presented as such (this Ottolenghi soup I have served as both dal and sambhar to indian folks, and eaten as soup with croutons or toast on my own, but even a simple moong or masoor dal is an easy start — with rice, or naan to dip).
On to Thai-adjacent: Kerala stew swaps lemongrass for whole spices and is stupid-easy (we love it vegetarian too).
I have recommended and gifted Madhur Jaffrey’s Quick and Easy Indian often — her recipes are home-style but adapted to a western kitchen and eating style.
And for a shortcut, while I don’t like most ready sauces, Maya Kaimal has a “fresh” (refrigerated) range at Whole Foods and Costco that doesn’t have that bottle / preservative aftertaste — includes a coconut curry base iirc.
