Apart from ethical or environmental concerns, one of the best decisions you can make nutrition wise is to vary your intake a lot and one of the worst is to try and subsist on a limited range of foodstuffs.
When you are unable to rely on old faithfuls, especially meat and dairy, you have to explore other possibilities and really dip into the weird.
One quick and easy trick is to eat “colorful food”.
Eating a meal that has lots of different colors increases your odds of getting a broader variety of nutritional content.
Fasting seems to be good for you, for example, because it stimulates the body to consume malformed proteins. Changing intake up from one day to the next also should help the diversity of the gut biome and the activation of several metabolic pathways without 'overheating' any of them.