The easiest way to work out a good combination is to consider the weight of the meal. Heavy Tomato Sauce or dark bean based dishes go well with fruity reds.
Think about choosing a syrah, cabernet sauvignon or even a chianti with the richer vegetarian dishes.
For a wine to go with lighter egg based vegetarian dishes you should find that white wines such as sauvignon blanc go well.
For mushroom based dishes we particularly like pinot noir.
With a really spicy dish a german gewurztraminer can be delighful.