Tell your kids they are perfect the way they are, but they shouldn't stay where they are forever because growing, testing the limits, and evolving make life better and more fulfilling.
You can tell your kids they are perfect and don't need to change - which could cause insecurity when they recognize their own shortcomings - or tell them they are terrible, which would undermine their sense of self-worth and confidence. There's a happy middle ground.
Don't make a different meal for every person, but make buildable meals. And, I do this with my kids, try to expand their palates gently.