Hi, I'd take a look at the high quality organic pellets such as Harrison's and Totally Organics (TOPS). I've seen proof of the high nutritional value of Harrison's by perfect blood work results over DECADES in a bird who likes to eat little else. Also vibrant beautiful plumage.
Another brand, Totally Organics uses a cold press method of processing, which simply put, keeps the maximum amount of nutrients in the finished product.
Some people choose to feed a quality seed mix instead of pellets as their dry food.
The vegetables packed with the most nutrition are going to be your dark greens and dark orange color. As far as what kind of vegetables your bird will like best, you'll have to experiment. Just avoid toxic foods of course (a good list with some suggestions is included in Timothy's post). Some fruits have more nutrition than others. Some are mostly just sugar water with vitamin C. Though their natural sugars are not as bad as sugars in processed foods, and they can add a bit of variety to the fresh food bowl.
Some people do sprouted seeds, which have an excellent source of phytonutrients. What are phytonutrients? Click here for an easy explanation.
What Are Phytonutrients? Types and Food Sources There are some instructions for sprouting in this forum if you look under the search field.
Also, what you will hear people refer to as 'mash' is also popular. You can get creative as to what it contains. Legumes such as beans and lentils, various types of grains, variety of small fresh chopped items, even eggshells, etc, etc. (There are probably recipes under 'search'). A popular way of storing mash would be in ice cube trays for a conveniently sized portion to pop out and thaw.
Many people regularly give their bird(s) whatever the humans are eating. This can be good if you're a health nut, but bad if you're mostly eating processed fried foods for every meal... A little bit of a "decadent" food every now and then won't hurt. I would just use a good dose of common sense when feeding people food, and remember how tiny their bodies are in proportion to the amount of food you give.
As you can see, there are many options, and not everyone does the same thing. Some people do all of these things, while some just do a couple of these. Diet is a very controversial topic you'll find

. In time, you will form your own opinion and come to settle on what works best for you. Hope this helps
