Manĝi is the right word here. You could say manĝado de but that would be 1) long-winded, and 2) ambiguous, as it's not clear if the vegetaranoj are eating or are being eaten. So the by far most common solution is Manĝi la vegetaranojn (don't forget the accusative -n). You're also not using the infinitive as a noun. It's still just an infinitive, that's why you don't need another preposition afterwards.
Hmm, I haven't met such affixes or expressing. In a lot of cases, we just add -o to the noun. Lerni - lerno (to learn - a learning).
And I think mangxo is a good word for it. It is translated like "meal"
If you use infinitive like subject (noun), it means process, action. It will be like verbal noun!
We can't use mangxanto in this case, because when we add -o to -anto, it means a person or a thing who do it.
As one who has eaten bear in my younger years (while I was traveling in the outback of Alaska, etc.) I found the taste to be a bit "gamey" but tender. There's a lot of fat in the meat, but it can also have a bit of a fishy flavor. (One old Indian I stayed with said that after a while of eating bear meat one can tell what the animal's diet was, just from the flavor)
So the flavor's not bad, but I don't foresee it replacing bacon anytime, ever.
So my English brain immediately heard that as "The bear s***ed the vegetarian."
And then I laughed, because really, that would be the next thing that happens, right? ;)
The bear likes the vegetarian. The vegetarian option on the menu (contains fish)
Vegetarano Rostita ₱435.75
Hakita vegetarano kun fritita melongeno kaj marinado en nia subskribo saŭco. Venas kun rizo.
Aldoni lakto-fiŝo ₱96.00
Aldoni terpomo ₱96.00
Vegetarian Roasted ₱ 435.75
Chopped vegetarian with fried eggplant and marinaded in our signature sauce. It comes with rice.
Add milk-fish ₱ 96.00
Add potato ₱ 96.00
How is the meal vegetarian if there is a human in it? Well the said human in it had a vegetarian diet.
vegan adj vegetaĵa; n vegetaĵano