If you have a child with food allergies, you are most likely dealing with sensitive skin issues as well. I searched high and low for a foaming "fragrance" free soap to making washing hands fun for my daughter. I couldn't find one. For our regular foamy hand soap (that my husband and I use) I use a small amount of shower gel or bubble bath mixed with water.
I tried this with Aveeno Creamy wash. I simply put a couple tablespoons in a well-cleaned soap dispenser and filled the rest with water. Shake it up to mix it together. I suggest adding a small amount of soap to see how it foams. If you don't add enough it will be watery. If you use too much soap it won't foam. It's pretty easy to figure out and little one's just love foamy soap! Plus you don't need to worry about itchy skin when you are just trying to clean messy fingers.
I stock up on Avenno soap (and other products) when it is on sale and couple the sale with manufacturer and store coupons at Target. If you are patient you can get some really good deals.
A little update
4 years ago