There is no single dish that will provide everything you need. Instead focus on cleaning up your diet by eating from a variety of healthy food groups.
For example, I try to eat cruciferous vegetables every day, since that category includes spinach, broccoli, cauliflower, kale, Brussels sprouts, chard, etc., there’s a lot a variety to change things up on a daily basis.
I’m going to consider this a purely theoretical exercise, but the following would get you pretty close to healthy - and definitely closer than most people are getting:
The science of gut health is clear: you need to eat 30 different plants a week. So your ideal meal would have to contain 30 plants. I guess you could make a smoothie.
And then for volume and calories. I guess you could go with oats for breakfast and lunch and beans for dinner. And if you’re going to go completely without supplements, eat fish 3 times a week.
Of course oats and beans are pretty boring bare, but then if you really want to eat the same thing everyday, boring isn’t what you’re afraid of.