This isn't exactly authentic, but it's incredibly tasty.
2 tbsp butter
1 medium onion, diced (about 1 cup)
1 clove garlic
3 stalks celery, chopped (about 1/2 cup)
2 tbsp flour
1 can diced tomatoes, undrained
~1 cup water or maybe vegetable broth (I used 1/2 the can)
2 tsp curry
1 tsp soy sauce
1 lb cooked shrimp (DH picked up tiger prawns instead. mmmmm)
Kosher Salt to taste
Melt butter in the skillet. Add onion, garlic and celery. Cook until soft (you may want to add the celery first as it takes longer than the onion).
Mix in flour until incorporated. Add tomatoes, water/broth, curry and soy sauce. Stir well until bubbly. Taste, add other spices as needed/wanted (I added a bit of salt since I used low-sodium everything). Add shrimp. Reduce heat and simmer for 20-30 minutes.