Use tomato already growing -- if you don't have any ask gardener friend or buy overgrown plant at garden store.
Find a sucker. A sucker is a branch growing between two branches. They zap energy from plant so it helps plants to remove them. Suckers do not have flowers.
Remove by snipping off with scissors.
The cut sucker - it's about 4 - 5 inches long.
Shot glass or any small vessel that can hold water can be used.
Fill glass with water. Add tomato sucker stems.
They may wilt first few days but will develop roots in a week to 10 days. Change water if it gets cloudy. Add water if level drops.
Roots! Notice little nubs? You can plant to depth above them. I will remove that lower leaf before final planting.
Make hole bigger than rootball in the soil.
Plant and carefully add soil to completely cover roots. Soil level can be half inch above or even higher. I use cheap potting soil--the one without added fertilizer.
Here's your plant. Plant in ground or 5 gallon container after plant has rooted more in soil, 2 - 3 weeks. These plants grow fast so you could get a tomato crop in 60 days.