Soak the dried fenugreek in 3 tablespoons water for 15-20 minutes or until all liquid is absorbed. Set aside.
Place the tamarind pulp in a small bowl.
Cover with 1 cup of warm water; stir and let sit for 30 minutes or until softened.
Use your fingers to mash it a little.
Then push a bit at a time through a fine strainer with the back of a spoon.
Set the tamarind paste aside.
Meanwhile, wash the fish fillets and pat dry. Season both sides with salt and pepper. In a frying pan, heat 2 tablespoons oil over medium heat. Lightly saute the tilapia pieces on all sides, about 2 minutes per side. Place them on a paper towel to absorb the extra oil. Set aside.
Heat 3 tablespoons canola oil in a pot over medium heat. Add the chopped onions and saute until softened, about 8-10 minutes. Add the garlic and turmeric powder; saute for 1 minute. Add the coriander and fenugreek to the pot. Saute for about 8 minutes over medium heat or until herbs are fragrant.
Then add half of the tamarind paste, 1 2/3 cups water, salt and red pepper. Cover the pot and bring to a boil. Reduce heat to medium and simmer for 35 minutes.
Then dissolve flour in 1/4 cup of cold water; pour into the stew and stir well. Taste and adjust seasonings. Depending on your taste; add more tamarind paste, for more sour flavour (I added all the tamarind paste) or add more red pepper for spicier stew.
Gently place the tilapia pieces in the stew. Cover the pot and cook for another 30 minutes over medium-low heat. Do not stir the stew.
Place the Ghalieh Mahi stew in a serving bowl and serve with Persian Rice.