For what purposes do you want to become a vegetarian? And then eggs and caviar are the best friends of an athlete, but what if you are out of some religious beliefs and you can't? Although modern purchased eggs are unfertilized, so in theory it is possible.
There is no special need to remove meat from meat, just take it and do not eat it. But eat nuts, cheese, cottage cheese, buckwheat, oatmeal. Better in milk.
Walnut-chocolate desserts, dates are for the brains. Well, greens, where can we go without it. Lots and lots of greenery. Ideally, all sorts of molluscs - mussels, shrimps, but here again the question of the reasons for the sudden vegetarianism.