It depends on where you live. For example, I live in NYC and there's this app called "Too Good To Go" where you can buy food that restaurants might throw away at the end of the day (i.e. perishable goods they can't keep until the next day).
You get a fair amount for like just $5 and it's enough to feed 2 people. And because it's perishable, it's generally pretty fresh as well, but it's only available for some cities.
If you aren't in a city that supports that app, another thing we do is just:
1. Flatbread + hummus + tomato + sausage
2. Smoked salmon + avocado + rice cakes.
Simple, healthy, and fast.