What's your favorite food that balances cost, time, and effort with fiber, protein, and nutrition?

Hello everyone, I am awaiting a possible diagnosis pending A1c results. Even if results are better than expected my fasting blood sugar is definitely a bit high and I need to work on getting more fiber and protein and less sugar and refined carbs.

I struggle to find energy to cook a lot of the time and can't exactly afford a private chef. So I am looking for ideas and strategies that have worked for people.

Things that I have found to be helpful: Beans, whole grains, frozen cook-in-bag veggies, frozen fruits, the freezer/microwave dream team, trying new things and being flexible, probably other things I'm not thinking of

I am a caffeine fiend, though I don't take as much sugar as many people do, I drink so much coffee and tea that the sugar adds up. I am working on this and having success with stevia extract and flavor extracts.

I am very much new to this so thanks for any pointers :)