If you live with an inadequate grocery budget, and you're mixing soup kitchen meals with home-cooked meals, then you want to make sure your grocery store purchases actually save you money and give you more free, productive days that are your own. For a soup kitchen user, the ultimate luxury is being able to have at least one meal at home, per day. Ideally, two meals, breakfast and dinner.
There's three foods that will save you lots and lots of money, lots of time, and lots of headaches. The lentils and eggs are especially good when combined with vegetables from the garbage or food banks. None of these things need refrigeration (even the eggs), and they're super cheap and easy to prepare:
Lentils are good poor person food: they're cheap, they're high in protein, and unlike beans, they can be boiled up without pre-soaking, so they're fast to make. Maybe a half-hour. Just stick them in water with a tiny bit of salt, bring them to a boil and hold them at a simmer, and after about fifteen or twenty minutes of this, you start checking them every ten minutes or so to see if they're soft yet. While they're coming to a boil, add any veggies you've got lying around. Chop the veggies up super fine, or shred them with a cheese grater. Season them with whatever spices you want. The result is a really clean, neutral meal. The perfect hangover meal. If you've always got some of this lying around, you'll always have some protein handy.
Oatmeal is so easy to work with, and has such a nice balance of protein, carbs and fats built into the oats, that it makes a great breakfast, as well as a great evening snack. There's no real point in using instant oatmeal, because it doesn't have much nutritional value, and doesn't really save that much time. Just regular oats are super quick, and fine-cut oats are even faster. With any oats you have, all you have to do to cook them perfectly is make sure they're covered, bring them to a boil, cut the heat, and let them sit there 'til they're cool enough to eat. By that time, they'll be perfectly cooked. Use twice as much water as you have oats. A cup of oats is enough for one meal. Add a tiny amount of salt at the beginning. While it's coming to a boil, add raisins, nuts and some chopped-up fruit if you have it. But even if you can't add anything, it's still good. To make it ultra deluxe, stir in a bit of sugar and a bit of coconut oil, after you've cut the heat, before it's started cooling off.
Eggs are the quickest protein you can find, and it's easy to make them taste great. Heat them up in whatever way is easiest for you. But if you chuck a few eggs in a pan, break the yolks, and grate some veggies, like sweet potatoes, yams or greens, over top of the eggs. Then later on you can fold the eggs over and you've basically got a lazy-person's omelette. Dash of salt at the beginning, pepper too if you have it, basil's great, and yeah, any finely-chopped stuff you can add to it.
Whether you're working with a campsite fire pit, a community kitchen at a drop-in, or a ghetto kitchenette in a rooming house, these three foods can tie your days together, and bracket those big mid-day soup kitchen meals with a little home cooking.
If you do start doing breakfasts at home, you'll end up wanting to do coffee, too. So here's a little bonus tip for making yourself great coffee for free: Used espresso grounds from coffee shops. You know the little puck-shaped things that they throw out after making espresso out of them? Get about five of those and you can boil up an amazing pot of coffee. Like, a whole pot. So like, three big cups. And it's way better than soup kitchen coffee. Just bring your water to a boil, add the coffee, be prepared for it to boil over, so maybe put the pot in the sink when you're adding the coffee, and stir it in gradually. Then when the coffee's added, put the pot back on the heat, cover it, bring it to a boil, and boil it 'til it stops being foamy. Then either wait for the grains to settle before pouring it into a cup, or use some cheesecloth to strain out the grains as you pour the coffee.