I agree with some of the others, if you have room, definitely try and grow your own tomatoes, spinach, capsicum etc. I used to grow those (plus a wide range of herbs) purely out of pots at my last place. Those three are quite nutritious, but they're also my faves so choose whatever you love to eat
If you have no room (or particularly enterprising possums which I'm currently dealing with), buy what you can from markets in the way of lentils, beans, grains and fresh veg. You want to go for max nutrition in what you do eat.. brown rice, lentils, chickpeas, kidney beans.. cook those and mix with fresh spinach and sautéed carrots, mushrooms, sweet potato and other veggies with black peppercorns, garlic powder, cumin and chilli powder? yum. Make big batches at once so you can buy in bulk..
Good luck! xx