Tempeh is a special type of food that starts off as soybeans. These soybeans are then cooked, mixed together, and put into a special container where they are left to sit and grow for a while. During this time, something called fermentation happens. This means that special little guys called "microbes" start to grow on the soybeans and change them into something new called tempeh.
Think of it like planting a seed and watching it grow into a big plant. The soybeans are the seeds, and the microbes are like the sunshine, water, and nutrients that help the plant grow.
Once the tempeh is ready, it can be eaten in all sorts of ways. Some people like to fry it up in a pan and put it in sandwiches, while others prefer to crumble it up and use it like ground meat. People like tempeh because it's full of protein and other nutrients that are good for your body.