An alternative to Tinned Fish ?

I am constantly hungry which the Internet leads me to believe is best solved by eating protein rich foods. Specifically I am looking for food to each for lunch at work so it needs to have zero preparation time (like opening a tin of fish or beans). I tried baked beans but the sugar content of the common brands concerned me so instead I opted for fish which I have been eating every day for years now. Interested in decreasing my meat consumption I am wondering if there is a vegetarian alternative. In summary I am looking for something with:

0. Vegetarian
1. High protein content
2. Zero prep time
3. Portable and preferably single serving.
4. Gluten free, as I am Coeliac

So any ideas ? Some type of tinned beans would be perfectly acceptable if anyone could tell me where I could find just that; baked beans, optionally in sauce, (as opposed to baked beans in sauce + loads of sugar/sugar substitute). For reference my lunch currently consists of:

Almonds, hazelnuts, grapes, a mandrin orange, carrot, sugarsnap peas, broccoli, cucumber, lettuce, corn cakes and a tin of tuna.

Thanks,

Usjes.