Protein is essential for growth, healing and every day bodily function. It is relatively easy to acquire your necessary protein requirements if you think of essential amino acids rather than protein.

Protein is made of amino acids. If you eat protein, the body breaks it down to amino acids first, and then rebuilds from these amino acids the proteins that you require.

What you do need to focus on are Essential Amino Acids. Essential amino acids are the amino acids which your body cannot make, and therefore you need to acquire these through food.

Animal foods - meat, eggs etc have "complete protein" which essentially means that all the amino acids are present. A food with "incomplete protein" is essentially a food which does not contain all the essential amino acids.

The good news for vegetarians is -
  1. some foods such as soy beans, spirulina and quinoa are complete proteins, that is - they do contain all the essential amino acids.
  2. a combination of foods eaten together or during the week can supply all the essential amino acids.
As long as you eat a variety of different foods, there is no reason why you should be lacking in protein! However, if you are trying to build muscle for whatever reason, you may want to focus on foods with a high protein(amino acid) content.

The 8 essential amino acids are:
isoleucine
leucine
lysine
methionine
tryptophan
threonine
phenylalanine
valine

The aim is to eat foods that have a high proportion of protein, and most of the essential amino acids listed. If a certain food is missing one of the essential amino acids, then make sure you match it up with another food that has a high proportion of that particular amino acid.

Here is a table I've compiled from a couple of different websites comparing different legumes as well as meats:


 protein in grams per calories ratio
peanuts 35
773
0.045278
lentils 17.9
230
0.077826
chickpeas, garbanzo, bengal gram 14.5
269
0.053903
lima beans 14.6
229
0.063755
kidney beans 15.3
225
0.068
split peas 16.3
231
0.070563
mung beans 14.2
212
0.066981






egg 6.3
77
0.081818
milk 8
120
0.066667
chicken 35.1
196
0.179082
pork 31
358
0.086592
turkey 34
178
0.191011
tuna 14
60
0.233333

This table shows that legumes can have quite a high ratio of protein to calories. In fact the legumes are comparable to milk, eggs and pork!!
"Unhealthy" meats with more fat content are not included in the table.

Now that you know how much protein you can get from legumes, you need to fill in the missing amino acids. Most legumes are missing methionine, the good news is that most cereals contain methionine but are low in lysine. Therefore if you consume both cereals and legumes in your diet then you have made a complete protein from your combination meal - with methionine from the cereals, and lysine from the legumes.

Meal combinations to consider include - rice with lentils, rice with beans, tortillas with beans. Remember you can consume different amino acids on different days and consume your complete protein over a whole week, you do not have to consume all the amino acids in one sitting!

Try these websites for some quite thorough lists of protein contents of foods:
http://www.highproteinfoods.net/legumes
http://www.healthaliciousness.com/articles/beans-legumes-highest-protein.php

http://www.nomeatathlete.com/vegetarian-protein/

Interesting reading... Good Luck :-)