Heat oil in a pot and add seeds, fennel powder, turmeric, ginger. Cook for a few minutes on medium heat-stir. Add onion and leeks, saute for 5 mins, stirr. Add remaining ingredients and 10-12 cups water. Bring to a boil and then simmer on low for 1-2 hours. Stir occasionally. Depth of flavor will deepen with longer simmering.
Add toppings for taste when serving. I typically don't eat parsnips but you can.