If it was pea and ham soup then I'd go with split peas, but for freshness you really can't beat just using fresh vegetables. I saw Gordon Ramsay once make a broccoli soup that was nothing more than broccoli boiled in a bit of water then blended with a bit of oil and salt. Give it a crack, there's about $5 worth of ingredients in my soup so if you don't like it it's not an expensive mistake.