This dish is very tasty and I enjoy this dish
The dish is tasty.
It is reasonable to assume that only one dish is mentioned, so 'the' is just as appropriate as 'this'.
exists e1 s1 x1 x2.(n_dish(x2) & n_person(x1) & n_dish(x1) & Theme(e1,x2) & Actor(e1,x1) & v_enjoy(e1) & r_very(s1) & Theme(s1,x1) & a_tasty(s1))
exists s1 x1.(n_dish(x1) & Theme(s1,x1) & a_tasty(s1))