Twin dad, we have one of these in our first floor bathroom. We sometimes move that to the kitchen:


But if both want to participate, then we often just put the kitchen table chairs, which are metal framed dining room seats next to the counter and they stand on those.

I use a folding steps tool that has 2 steps. It doesn't have sides, but does an angled bar along the steps and I kind of handle at counter height. I think we got it at Bed Bath and Beyond, I've also seen similar ones at Home Depot.

relate question: What do you use to have your kid's stand at counter height? Just a regular step stool? Something with sides on it?

My kid's job is often to wash the veggies. And sometimes to taste them.

Twin dad PP again. Last night, they wanted to help, so they helped make salads. I washed greens and put in the spinner. They pushed the spinner. When it stopped, I had them fill the bowls. I cut up toppings and they got to put toppings on the salads. Yes, it took twice as long to make salads, but they did enjoy "cooking".

The side benefit is that they were eating salad toppings as I cut them up. They each had two tomatoes (Medium Compari tomatoes), several cucumber slices, some julienned carrots and some broccoli florets. By the time we sat down to eat, they had had enough veggies that I wasn't concerned if they did or didn't eat any more veggies (but they had more).

NP here.. these are great ideas and I am storing them away for my 4YO
She loves to be my "chef helper" <- thank you, preschool! and is very good at dumping premeasured things into mixing bowls, mixing things in very large bowls and counting... ie please count out 12 cherry tomatoes and put them in this bowl, or count out how many cups of broth I am pouring in, etc.
I haven't really worked on knife skills with her except when I'm cutting really, really soft things like melon, I might start doing that!
I have found that she really loves being able to pick out ingredients, which turns into a kind of mommy-top-chef moment in the store as I try to figure out what to do with "cranberry beans" or some such. but it's led to some interesting discoveries.

Measuring and dumping. Stirring (yes even on the stove). He can feed and operate the food processor.

This plastic cheese knife is the shape of a chef knife for little hands. Sturdy enough to chop carrots, celery, etc., but plastic so they can't hurt themselves. It's also a great cheese knife.

Nice to get them an early start on knife skills.

http://www.amazon.com/Fairchild-Red-Cheese-Knife/dp/B00CAYTUMS/ref=sr_1_3?ie=UTF8&qid=1420568263&sr=8-3&keywords=plastic+cheese+knife

Salad spinner! Haven't met a toddler yet who doesn't love making stuff go round and round.

My toddler LOVES juicing! He helps me put in all of the fruits and veggies and then loves drinking the fruits of his labor. And it's a super sneaky way to get raw veggies in him! Tip: throw in a beet to make it more vibrant and less murky in color.

3 yo twins who have been helping me cook for about 6 months, so we started about where you are now. When there are meals or courses that they can help, I measure things out, put them in bowls and then they each get a bowl of something and instructions.

For example, they help me make pancakes on weekends. I measure out the various ingredients and put them in small bowls. I crack the eggs into a measuring cup. I will put the honey into the bowl (just too difficult and messy) and then they each get a whisk and they alternate, A will whisk while B adds his bowl, then B will whisk while A adds his bowl. I get an extra large bowl out so that they can be vigorous when whisking. They have helped my wife make cookies and she does the same thing. She also makes breakfast muffins with them and they do the same as with the pancakes. They have helped me make pizza. I put the dough down and then they help put sauce, cheese and toppings on the pizza. We also have a toy kitchen that is in the eat-in area of our kitchen. Sometimes when Daddy or Mommy is cooking on the stove (the one place they can't help), they can cook at the same time in their kitchen.

For dinner, they sometimes help with making salads, breaking up iceberg lettuce, taking spring mix veggies out of the bag and putting in bowls, after we cut up veggies, they can add them to the salad. Mom and Dad and twin A eat salad, twin B doesn't, but still helps make salads sometimes. They help move items from the cooking area to the table and help set the table. As long as we can find things that don't involve knives, the oven, or stove, we'll try to get them to help.

Get a kids cookbook like "Pretend Soup." Basic, kid friendly recipes and good illustrations.