Tomatoes are a food item that can be farmed as a sustainable food source. They replenish and have a decent saturation of 4. They are only initially obtainable by killing Frosts. Because of this, an inexperienced player should not attempt to obtain these, as frost can be considered as a very dangerous enemy especially early on.
And by the time the player is ready to take on frost effectively, they'll have either a crop farm of bread/wheat and/or meat farm, making tomato a food that can be used for travel throughout Taiga biomes in emergency, but is dicouraged for farming purposes early on. By placing a tomato in a crafting grid, you can acquire 4 Tomato Seeds.