I used to teach pre-school and we cooked EVERY day, except for field trip days. We learned to SMELL things - particularly spices, etc. We ALWAYS took a "courtesy bite" just to try it. If they didn't like it, that was fine, but at LEAST try it. Don't make a big deal out of it one way or another, just KEEP encouraging him to TRY TRY TRY.
I had girls who initially held their nose and wouldn't try things. We just kept talking about it and asking them to try and they watched other kids try and LIKE IT. They were then encouraged by them. We also talked about WHY eating those foods were important. And yes......a THREE YEAR OLD CAN begin to understand the WHY of good nutrition. You just have to present it on THEIR level. At the end of the school year, NONE of these girls had that problem any more.
One mother even told me that she was amazed at what her child would try. She said that she now tries ANYTHING she puts in front of her and that her daughter, now 4, was also continually encouraging her 2 year old little brother to try new things. We always said, "It's so much fun to try new things. When you don't try, you miss out."
There are MANY simple ways to encourage that. When at the grocery, let HIM pick out something NEW from the produce section and TRY FIXING IT TOGETHER. My roommate's 5 year old & I experimented with taffy this past weekend. It was FUN to try something new. She LLLLLLLLOVES helping and now thinks she's Rachel Ray!
Let them choose the vegetable or fruit rather than just put it in front of them. Let them start making choices NOW. They will carry that with them throughout life. I know.......I have kids that I had in preschool who STILL make choices based on what I taught them in preschool.
They knew what proteins, fats and carbs were......good and bad and WHY their bodies needed each of them. ANY TIME you present something, attach the WHY behind it. EVERYONE is much more apt to apply something that they know the WHY behind it rather than...."just because I said so".
If you don't know.......LEARN! Find out what nutrients are in peas, green beans, broccoli and HOW your body utilizes those nutrients. Needed for eyesight, immune system (keeping you from getting sick, strong bones, etc.) THEY ARE NOT TOO YOUNG TO START! You might both learn something. It can be good for BOTH of you!!
I've been teaching Abbie since she was two. She has WWWAAAY more knowledge about nutrition than most adults!!! THANK GOD!