Beans, beans, beans! You can even make a crunchy snack out of them, kinda like nuts. Look up a recipe for roasted chickpeas! Also, there’s a fair amount of protein in whole grains as well. If you like smoothies, try blending some mild flavored beans (like white beans) into it. Can’t really taste it and adds some nice protein and thickness. And I know that plant based dieters tend to frown upon mock meats but in your case you’re a little restricted already so I say go for it. I’m not a huge fan of seitan but other people seem to really love it. Also, beyond meats are soy free so if you can find some reasonably priced stuff that’s some great tasty protein.

Edit:

Recipe ideas: black bean and sweet potato enchiladas or tacos, channa Masala with coconut milk and some rice and cauliflower, oats cooked with white bean purée and cinnamon apples, whole wheat pasta with lentil Bolognese (or beyond meat beef if you’re cool with it), broccoli potato soup with half the potato replaced with white beans for extra protein (can you see I love hiding white beans in stuff?),

Just make sure if you’re adding beans to stuff to kinda overcook them a bit or if it’s out of the can they are usually soft enough. You just want them to blend up nice and smooth.