Caramelize the onions in a large, wide pan with olive oil. Start over high heat and, as the onions begin to color and all the juices cook off, reduce the heat so they do not burn. This will take an hour or so (up to 90 minutes).
Meanwhile, add lentils, bulgur, water, and seasoning to a medium pot and bring to a simmer. Cover and simmer over low heat until tender (20-30 minutes). Add extra water, if necessary.