So this morning, I wandered across the back yard and pulled up a medium-sized spinach plant (one that was crowding several others), and a spring onion. Then back inside for a little omelette — I don’t want to sound like one of those Alice Waters/Richard Olney cranks, but I have to say, growing my own produce has entirely changed my cooking. All that emphasis on freshness, and not mucking with the flavor of the ingredients — it makes much more sense when you’ve got produce so fresh that it was growing two minutes ago. (For instance, the French recipe for…