I make my soups in a crock pot slow cooker and cook them overnight.

I start off with yellow lentils and water in the crock pot and set it on high.

Add:

One large can of whole tomatoes.
One package of frozen soup vegetables.
One large onion sliced up.
Marjoram.
Curry powder.
Garlic powder.

I am careful not to over season at the beginning. I adjust the seasoning in the morning to taste and the let it cook on low until a half hour before serving. Then I turn it up to high.