Ok, so we approach this a few different ways:
1. The "no thank you bite": this is the bite every person must take before they can reject it as yucky, unedible, disgusting, gross, barfarific... lol. It works really well for us. After that one bite, they are able to say no thank you and don't have to try any more, until next time it is served. I have found that my toddlers will say no thank you a few times, and then one day will happily eat it! lol
2. Smoothies. I stuff a ton of baby spinach into morning smoothies, as well as coconut milk, some frozen berries and a banana usually. Yum, full of healthy fat, and greens! They used to be totally unaware of the greens due to the berries, but now they help make them and we call them dinosaur leaves and talk about how strong they make us.
3. We make new foods an adventure. Today we went to the asian market and smelled, touched and saw so many vegetables and foods we were unfamiliar with. We made it a really fun outing, and both boys got to pick a new food to bring home to try. The five year old picked a dragon fruit, and the 3 year old picked garlic ramps! I picked a young coconut, and also bought some sashimi grade salmon, eel, and surf clam. We had a sushi night, dipped our new foods (new for the boys) into tamari, and talked about how interesting the garlic ramp mushroom stirfry was. They were so pumped to try so many new things, and we applauded them when they bravely tasted everything with an open mind.
4. Cheese sauce. Nuff said. This can make any vegetable edible.
The more I see the less I know for sure.