You are probably aware that a toddler’s development phase is the most crucial stage of our lives. Between six to 35 months, we not only grow physically, but also mentally at a rate unparalleled in our lifetime. This is the time that the foundation for our future health is laid. In fact, children between 1-3 years require twice the calories and iron that we do as adults.
What they require
It is therefore not enough to feed the child what you may eat yourself. Adult diets may often be bulky and your pre-schoolers require energy and nutrient-dense diet as their stomach capacity is limited. What constitutes a good diet for you may not be nutrient dense enough to meet your pre-schooler's Recommended Dietary Allowance (RDA). 
As opposed to macronutrients like carbohydrates, proteins and fats, micronutrients are required by the body only in minute quantities. However, these small amounts are central to their healthy growth. For instance, DHA, or docosahexaenoic acid is essential for brain and retinal development at this stage and is found in fatty fish.  Certain oils like soya supply Omega 3 fatty acids but not preformed DHA. DHA needs to be synthesised in the body from the parent omega 3 fatty acid. Similarly, calcium and magnesium are minerals that are crucial for growth and found in milk and milk products, greens; zinc - found in peanuts, high protein foods like meat, legumes - stimulates growth, reduces chances of infection and boosts immunity and other enzyme activity. And these are just a few of the essential vitamins and minerals.
Nutrition
You may feel that your child is already getting adequate amounts of all these crucial nutrients, but take a look at the figures. Even educated mothers from relatively affluent households may often fail to ensure an adequate dietary intake for their little ones. We are all familiar with the reasons - fast-paced lifestyles that tend to make cooking traditional recipes difficult; the fuss that children themselves create when faced with green leafy vegetables and plain milk; their insistence on less healthy alternatives like potato chips and soft drinks; and of course, the tendency of kids at this age to want to eat meals on their own rather than being fed by an adult… All these might lead to gaps in their nutrition. However, there are solutions available.
What you can do 
Exposing your child to a wide variety of flavours and textures at this stage will help to lay the foundations of healthy eating habits that will stay with him or her, life-long. You can make regular mealtimes interesting and a learning experience for the child - try involving your little one in the preparation of his or her meal.  Encourage them to ask questions and have them assist in the process whenever feasible. Periodically feeding them small, nutritious snacks is a better idea than trying to force feed them three meals a day. Ensure that you have a supply of healthy munchies such as fruits and roasted whole grain snacks ready at hand. You can also vary your cooking methods to maximise the nutritional value in each meal. For instance, minimizing the heating/ cooking duration helps retain essential vitamins to some extent.
Steaming is another option because this causes lesser loss of nutrients than frying. Soaking cereals and pulses before cooking boosts the nutrient value of the food. Digestibility of the cereal is also increased by malting (soaking cereals like jowar (barley) and others overnight). These can further be added to milk for a tasty and healthy liquid snack.
It is important to use the water in which cereals or pulses are soaked, so as to retain the B- vitamins that get mixed in the water.
Sprouting is another good option. Moong dal for instance, if sprouted and served in an appetising salad, boosts vitamin intake and encourages amylase production which, in turn, improves digestion and reduces colic to which youngsters are so prone.
Finally, remember to always wash fruits before cutting and not after, as this helps retain essential nutrients.
The author is a doctor at the Kanchi Kamakoti Child’s Trust Hospital