surely, any veg is better than none? even if it has been frozen and reheated, that's better than what he's eating now...nothing?
i can only say that my first was exactly the same. and her cookbook was a godsend for us. once he realised we were sneaking veg in, i started offering him a choice. he always gets 2 to choose from. and he always chooses. i don't make him eat a whole bowl, rather 3 or 4 pieces. that way, i'm winning the argument and he's getting used to eating some of the veg. he now loves: carrots, corn (in sauces, fried rice, on the cob, as a side), mushrooms. will tolerate: peas, long green beans, romaine lettuce, choi sum, bak choi...
fruit: strawberries, bananas, apples, grapes, watermelon (but only the juice in sago), dried mango (not fresh mango)...