Getting your kids involves with cooking might help. Starting a veggie patch so they see the process and getting invested into growing their own food.

I reckon it’s just a phase. Be patient, keep adding new foods and they’ll soon come round…..in time

Make Foods Appealing

Consider food temperature. Most children do not like very hot or very cold foods.
Consider food texture. …
Consider food color. …
Serve foods of different shapes. …
Balance food flavors. …
Include some well-liked foods in every meal. …
Introduce new foods with familiar foods. …
Serve a new food several times.

There are so many wonderful ideas on line about how to make food interesting.
I use biscuit cutters to make sandwich shapes.
Tell them that today is a red day so everything on their plate will be red (or whatever colour) then give them cherry tomatoes, fresh capsicum, chopped apple, dried cranberries, Babybel cheese, little sausages with tomato sauce – use your imagination.
Chop up ingredients and get them to make their own sandwiches and wraps.
Get them to help you to grow vegetables and involve them in cooking.
Ask them to plan a meal. Look at recipe books (or just the pictures) together.
It’s about enjoyment as much as about eating.
Good luck

Make food fun. Take them grocery shopping with you. Read the ingredients and try something new. Let them pick while at the shops!

Serve foods of different shapes,colours.Make sure to include well liked food with when introducing new foods.