Smoked aubergine can have a fishy taste (look up 'mouttabal'). Fried beans can have a bacon-like taste. But mostly it comes down to the flavouring - remembering how key rosemary was to chicken, thyme to beef etc.. For instance I have made amazing crispy duck out of baked inari (until dry) then marinated in hoisin and herbs, then served in little pancakes. I've made pulled pork out of jack fruit and shredded mushroom with the right seasoning and cooking methods (smoked/BBQ'd). I've used a blended combination of black pepper,
chickpeas, kidney beans, and kelp flakes and spring onions to make tuna. I've used black salt for a sulphuric taste when I wanted to mimic egg, and I'm picking up new techniques all the time.