When I'm lazy, I buy packet mixes of sausages and burgers that you just add water to then leave for 10mins and cook. I saw a new one that's sunflower seed and vegetable burger so I got it for variety. Turns out it needs a medium egg as well as the normal water. I don't ever use egg replacers so don't have purpose made ones or flax seed as well as being a bit clueless about them.
They are mostly dried TVP (15%), rusk (the wheat additive, not those biscuit things) oats and wheat gluten(seitan)- in that order. The ones I normally get (no egg needed) are rusk (30%) and TVP (25%) so I assume they are different enough that I can't just ignore the egg.