Mine is a big fan of a dippy egg, which conveniently can be breakfast, lunch, or tea as needed. Poached is easier for her to do more independently, but she copes with soft boiled with a little help.
We also make veg & cheese muffins – if you use something like courgette or carrot, it just about vanishes, but something like spinach and red pepper gives a more distinct, but still pretty mild flavour. Also a fruit version, banana and cinnamon is our standard, but pear, apple, tinned pineapple, and probably others I'm forgetting have all been successful. The fruit ones usually have a finely grated carrot in there as well...
Pesto pasta, can blend broccoli or spinach into the pesto if you want.
Egg fried rice also goes down well here, and if you chop the veg fairly small, most of it seems to get eaten. Also chili beans and rice (mild, unless he likes a bit of spice), one pot, works with most sorts of veg (again, chopped small), top with a little grated cheese if you like.
Roasted root veg might also tempt him to eat more visible veg (easy, if not fast).