food

Chili, curry, large bowls of leafy stuff (salads and slaws). Pasta dishes can be ramped up easily too if you have the large pots to cook a ton at a time. Seasoned rices good for large amounts of starches. Stews/heavy soups can be perfect as you can often make them cover a lot of foodgroups and thus they can be the singular thing you make if people don't mind. A 10-cup rice cooker might not be enough to make a large curry/stew/etc for 50 people though, that might be enough for 10-20 I'd think, you'd need to get a really large pot (restaurant supply will likely have? But it may not be super cheap). Its hard for me to say personally because I don't think I've ever tried to feed more than 10-15 people at a time. A bowl of stew is probably a bit more than a cup though, try pouring cups out into whatever bowl you would want to serve with to see how much it takes!

Recipe I would suggest soup/stew wise: https://www.twopeasandtheirpod.com/italian-sausage-tortellini-soup/

To make it vegan/vegetarian you can replace the sausage with soyrizo, which changes the base flavor quite a bit but not at all in a bad way. The cheese tortellini can be replaced with any number of other pastas, especially as tortellini tends to be expensive. The soup base can be veggie stock. I've made this on a number of camping trips and it can be quite filling. I would also add white beans and/or chickpeas to add more nutrition/filling. Can also add spinach in addition to the kale, or substitute spinach and remove the kale altogether. This recipe can be very cheap depending on how you're sourcing your ingredients, especially since soyrizo can be found for much cheaper than actual sausage.