Our pediatrician's advice about feeding kids is pretty simple: give them whatever you're having, puree it if necessary. If they eat it, great, if they don't, that's it until the next meal. So this is what we've done with Ollie and it's worked fairly well. It means I don't cook anything special for him, or feed him a second meal if he doesn't eat the first, or alter what we give him based on what we think he likes. When Ollie was younger, he loved broccoli. Then he pretty much stopped eating it whenever it was on his plate. These days he consistently eats avocado and sweet potato.
So the other night I made short ribs for dinner with sides of baked sweet potatoes and steamed broccoli. I threw some avocado on his plate because we had a bit leftover. I expected Ollie to eat his two favorites, ignore the broccoli, and try a bit of short rib. Instead Ollie ate all his broccoli and didn't touch anything else!
Now I see how important it is to not develop any ideas about a kid's "favorite" food, and to continue to expose them to everything. This was so eye-opening for me, even if he doesn't touch broccoli for another six months!