Combine all ingredients except cornstarch in a heat-safe mixing bowl.
Stir until dough starts to come together, then let sit in the bowl for 15 minutes so the water is absorbed.
Finish kneading dough by hand, adding cornstarch as needed, until the dough no longer sticks to hands.
If the dough still seems sticky, let it sit for a few more minutes, then knead again.
Video
Notes
Water - You can simply use warm or hot water straight for the sink for this recipe. The water does NOT need to be boiling.
If Dough Is Still Sticky - Depending on the humidity where you live, it may be helpful to let the dough sit for longer than 15 minutes so more of the moisture is absorbed. I live in a very humid area, so I let my playdough sit out for a couple of hours while I ran some errands. It was the perfect texture when I returned! It's also ok to add more cornstarch as needed to get the consistency you like.
Storage - Wash hands before playing to help keep the dough clean. Store in an airtight container at room temperature. This homemade playdough can last for weeks! If it starts to look dirty or smell bad, it's time to make a new batch.