I have this Stew Mix from sainsburys, it contain pearl barley, green split peas, lentille vertes, dried tomato and dried onion. The packet instruction tells me to cook and drain (really?) Or ad to casserole recipes biut I have never cooked casserole before and I don't have a casserole dish (the ones with a lid that goes in the oven) and I don't have a slow cooker. How can I cook and serve it?