Take curd and milk in a bowl. (Milk is optional if the curd is sweet. If it's even slightly sour though, it's better to add some milk.)
Add grated ginger, lemon juice, jeera powder, and salt. (You can grate extra ginger and squeeze one lemon in it. You can keep this mixture in the fridge for future use. It will stay unspoiled for 2-3 weeks at least, as lemon is a natural preservative.)
Mix the contents in the bowl properly. (Add the poha without washing only if you are using organic poha. Otherwise, you will need to wash it thoroughly before using it. Of course, you cannot wash thin poha because after washing it'll become lumpy/soggy. So if you want to use non-organic poha, use thick poha.)
Add poha and mix it properly with the mixture in the bowl.
Add chopped coriander and mix it properly. (Most toddlers don't like to chew coriander especially when it is raw. So adding coriander is optional.)
Feed your child dahi poha immediately after it's made as it'll become soggy if you keep it aside for some time.