Start with a good base diet(Harry Hamster in the UK is ideal,and fairly cheap too)then you can add whole and safe protein sources,with the amount and how often you feed them depending on the individual hamster's age.
Ideally animal protein(safe forms only)should come first,then after that you can feed other high protein plant matter as well.Broccoli,tofu,and certain beans(cooked only and of a safe variety)would be good for the plant side of things but there are most likely even more options
For animal protein(which is absolutely crucial as part of the diet of a hamster)there are lots of excellent choices.There's crickets,chicken(freeze dried or boiled plain with no form of seasonings or spices),mealworms,freshwater shrimp(high protein and much lower fat than mealworms,so they can be a much better choice in some situations),and turkey(same way as chicken).