Coat a large heavy-bottomed saucepan with oil and cook the onions until translucent. Add the celery, garlic, bell peppers
, and okra. Add the roux and mix thoroughly to pick up all the excess oil in the pot.
Next add the tomatoes and bring the mixture to a boil. When mixed, strain
the stock and add it to the pot, mixing thoroughly to prevent lumps. Cover with lid, bring to the boil and cook for 20 minutes. Clean the shrimp
and saute in a separate pan to get rid of any excess moisture. When they have turned pink add the shrimp and crab to the gumbo
. Cook for 10 minutes. Lastly, add lemon slices and chopped green onions