Orange juice concentrate goes wonderful with tossed veggies with a little garlic or other fresh herbs. Lemon juice concentrate works the same way. Also, using nuts can be a great way to add flavor as long as you are not using a lot. One or two tablespoons of roasted nuts brings out the nutty flavor. I experiment with lots of different mustards and different vinegars.
Balsamic vinegar has a very good flavor mixed with herbs.
I want to cook healthy so my daughter can eat, too. Steamed vegetables like green beans and broccoli spears are good. Kids would love to make chicken-style nuggets and instead of deep frying, you coat them with crushed corn flakes, small pieces, and cook maybe 10 to 15 minutes. Then kids can dip this in ketchup. Kids like finger foods.