We like to cook spinach in three stages, starting with 1/3 of the total amount cooked all the way, second 1/3 folded in and heated through, and the last 1/3 is placed on top, turn heat off and let it just wilt. Spinach is a wonderful vegetable but does have one annoying trait: it leaves a chalky feeling on our teeth. We believe the 3 stage cook method somewhat mitigates the spinach teeth syndrome because we’ve notice uncooked spinach in salads doesn’t routinely produce spinach teeth. Therefore we conclude eating raw and under cooked spinach produces less of the chalky tooth feeling than fully cooked spinach.
By the way the chalky feeling comes from undissolved oxalic acid that collects on our teeth. Oxalic acid is not food, and is to be avoided in large amounts. (Thus, we do not eat the leaves of rhubarb, for example). It actually interferes with the absorption of calcium (actually making it unavailable) and so we don’t count on spinach for our calcium. The nutritional contribution of spinach and other plant foods with oxalic acid is well worth eating for their available and dense source of many vitamins and minerals and antioxidants.
To clean spinach that is fairly clean to begin with as well as pre-washed spinach, put it in the basket of a salad spinner, a 1/3 at a time. (the basket should be only 3/4 full for proper spinning) Run the spinach in the basket under a gentle stream of cold water, turning while dirt runs off. Shake gently and spin in the salad spinner. Place into clean bowl till all spinach is prepared. Layer clean batches with paper towel after spinning. Hold briefly ( up to 8 hours) in refrigerator if not using immediately. Spinach done this way is ready for cooking and/or use in a fresh salad. In most recipes, no extra water is needed to cook it because of its own water content.
To clean very sandy (dirty) spinach, place into a bowl or clean food sink of cold water and swish. Lift out and change water; put back into cold water and swish; lift out and continue until no sand remains in water. Do this a minimum of 3 times. Remember a key to success when cleaning by soaking spinach in water is lifting it up and out rather than pouring it out with the water which will just coat the spinach with the same dirt and sand again. Three water baths also dilute any microbial contamination that may have been on the spinach. We always wash “pre-washed and bagged” spinach for good measure!