Hearty Cajun Shrimp Stew

1/2 cup peanut oil
1/2 cup flour
2 cup chopped yellow onion
1 cup chopped green onions
1/3 c chopped celery
1/2 cup chopped green bell pepper
4 garlic cloves, minced
2 to 3 tsp salt, to taste
1 tsp black pepper
1/4 tsp cayenne pepper (or more to taste)
3 bay leaves
1 tsp dried thyme
2 lb vine riped tomatoes, coarsely chopped
3 cups water (or shrimp stock if you have it)
1 tsp freshly squeezed lemon juice
2 lbs boiling potatoes (such as Yukon Gold), scrubbed or peeled and cut into 1 inch cubes
2 lbs fresh shrimp, cleaned

In a large heavy soup pot or Dutch oven, heat the oil over medium-high heat.
Whisk in the flour and continue cooking and whisking until the oil/flour turns a golden color; remove pot from heat immediately.
Add the onion, green onion, celery, green pepper, and garlic, stirring to combine.
Set the pot over low heat and continue cooking and stirring frequently for about 8 to 10 minutes or until vegetables are softened.
Add the salt, black pepper, cayenne, bay leaves, thyme, tomatoes, and water (or stock), and mix well. Simmer slowly for 30 minutes, stirring frequently. 
Add the diced potatoes and simmer 15 minutes longer.
Add the shrimp, cover the pot, and simmer over low heat for 15 minutes longer or until shrimp is pink and potatoes are tender.
Remove bay leaves and serve immediately.