I take a bunch of supplements and multivitamins

Jesus. You Americans (or your nationality of choice) are crazy.

1. If your food requires you to take a bunch of those, either:

• you are ill, and in need of professional help

• it is not food fit for human consumption.

2. Assuming first, you gaining weight might be hard, so if you have chronic health issues you should've mentioned that. Hormone issues can literally prevent "bulking up".

3. Assuming second option, to bulk up you need proteins and calories surplus and exercise. You can eat anything that meets your other criterions as long as you make sure of that, even paper or tree bark with coconut oil.

4. Soy is the best plant based protein source - highest DIAAS score. When you prepare it correctly (protein combining, predigestion) it goes up to 0.9, which is 2/3 of a chicken. Impossible meat has DIAAS score of 0.86.

This is the tricky part about vegan diet compared to omnivore diet - plants have lower bioavailability than meat. You need to aim into eating more proteins per kilogram, ideally 2.5g per kg of target weight (vs 1.6 - 2.0 on omnivore diet).

So if your target weight is 180 pounds/80kg thats about 200 gram per day of proteins. That is quite a lot, so likely you'll have to eat 5 dishes a day, each with about 40g of proteins.

That is massive amount of food, a lot of fiber, you might get bloated or constipated, so soy/pea protein isolate powder might be something you want to look into (to help you meet the protein threshold, not to be your main source of protein) - and if you're gonna incorporate it into your long term diet, you need to rotate brands and protein powder sources (rice, pea, soy, blends, etc etc).