You know when you go to the store and buy a head of romanie, green leaf, red leaf etc. Well when you cut of the stem (or what ever that part is called) leave it so the heart is still intact. Put it in a dish of water and set it in the sun and watch your lettuce start to regrow! It will even start to grow roots so you can eventually plant it in the ground so that you can get more nutrients from it.
Heres a pic of my week old escorole.
Heres a pic of my week old escorole.