Finely chop the parsley, green onions, celery, and green pepper.

Prepare a roux by melting the oleo in a pot over medium heat, then whisk in the flour until smooth. Cook, stirring constantly, for 30-45 minutes until the roux turns a light brown color.

Add the chopped vegetables and garlic powder to the roux and saute for 10-15 minutes, stirring frequently to prevent burning.

Gradually add the water, stirring continuously to prevent lumps from forming.

Add the tomato paste, salt, sugar, red pepper, black pepper, Worcestershire sauce, and Tabasco sauce.

Bring the mixture to a simmer, then reduce heat to low and simmer for 30 minutes, stirring occasionally.

Stir in the vinegar.

Continue to cook for 1 hour and 30 minutes, stirring occasionally.

Add the shrimp and simmer for 20 minutes, or until the shrimp are cooked through and pink.

Serve hot.