Dark Lentil Stew

I had wonderful guests today and made them lunch, which included this lentil dish. It's not authentic Indian or Moroccan, but rather a haphazard creation including spices from both cuisines. I made it in a slow cooker and, for various hosting reasons, used the high temperature setting. I imagine you could make this over a longer period of time using the low setting, or even let it simmer slowly on the stove.

1 tsp olive oil
1 yellow onion
2 cups masoor daal
1 tomato, cubed
1 small eggplant, cubed
7-8 mushrooms, sliced
1 garlic clove, thinly chopped
1 tbsp ras el hanout
1 tsp cumin seeds
1 tsp coriander seeds
3 cardamom pods

Heat olive oil in pan. Slice onion thinly and caramelize in the oil.
While this is going on, place daal, tomatoes, eggplant, mushrooms and garlic in slow cooker. Add the onion. Cover with boiling water about an inch and a half above the ingredients. Add all spices - be sure to crush the cardamom pods before placing them in the pot. Cook on high setting for three hours or on a low setting for longer.