i have a stovetop pressure cooker, I eat a lot of beans and grains - not every day but at least 2 or 3 times a week
beans & rice/quinoa is a good one - easy to make. they're cheap, easy to get, easy to buy in bulk, and have a shelf life of several years.
standard process, for me:
soak 1 1/2 cups of beans for 8 - 12 hours
add a bit of fat to the pressure cooker, then the beans, and just enough water to cover the beans. add pepper, dried chilies, bay leaves, etc - no salt though
cook for ~25 minutes at pressure, let the pressure reduce naturally
when done, add salt, if desired.
rice/quinoa - i prefer this to just rice by itself, the quinoa has a subtle nutty flavor.
same process for cooking as the beans, but you can add salt to the grains. ratio of grains to water is 1:2. i usually use 1/2 cup rice, 1/2 cup quinoa, and 2 cups water.
cook for 4 minutes at pressure, let the pressure reduce naturally
beans over rice or rice and beans all mixed up. doesnt really matter. this sort of meal is where sauces are really useful. I'm a big fan of hotsauce, but a soy-based teriyaki sauce or something similar works just as well. maybe just salsa? whatever you want really.
I do something similar just in a normal pot. Kidney or red beans soaked. You can pop the in boiling water and let sit for an hour if you weren't organised enough to do it 8 hours before.
Boil beans for about 30 mins until half cooked. Then strain.
In that same saucepan add a Bit of oil, onions, tomato (or half a tin of tomatoes) brown rice, paprika and some stock powder and black pepper. Chili if you want
Budget 1:1 rice to beans and 2:1 water to rice mix. Add more at the end if you need.
Other then the veg all things you can buy in bulk and store. Really filling. Good mix of protein and carbs. Add some frozen veg through or cook and have some on the side. I find broccoli is the best at filling you up.