Diets for infants and children should contain enough calories to support growth and have reliable sources of key nutrients like iron, zinc, Vit D and Vit B12.
Sources of protein are important too. A mixture of proteins throughout the day will provide enough essential amino acids without planning combination foods. Good sources of protein include: beans, lentils, tofu, nuts, seeds, tempeh and chickpeas. And if you eat dairy, then milk, cheese and yogurt are also good sources.
Good sources of iron include dried beans, tofu, tempeh, spinach, chard, cashews, and dried fruit. There are also iron-fortified cereals. To increase the iron absorption, eat a food containing Vit C, such as citrus fruits or juices, with the iron-rich food. Using iron cookware also adds to iron intake.
Sources of calcium include broccoli, collard greens, kale, tofu with calcium, and fortified orange juice and soy milk.
The adult B12 recommended intake is very low, but this is an essential nutrient so vegetarians have to be aware of good sources. Fortified foods, like cereal and yeast or soy milk, can be good sources. To be on the safe side, if you do not consume dairy products, eggs or fortified food, look for a non-animal-derived supplement.
It is always a good idea to meet with a registered dietitian, that your pediatrician may recommend, to insure that you and your children are meeting all their nutritional needs for proper growth and development.