1. In a deep pot, sauté onions in a little bit of oil until golden. Add remaining ingredients, except for pastrami, covering vegetables with water.
2. Bring to a boil, then lower heat and simmer until the vegetables are soft, approximately 40 minutes, adding some water if it steams out.
3. Blend soup until smooth. Add water, if necessary, to desired consistency. Garnish with diced pastrami.