Preheat the oven to 375°F. Grease two baking sheets.
Rinse the fish under cold water and pat dry thoroughly. Season them inside and out with salt and pepper and divide them between the baking sheets. Set aside in the refrigerator.
Heat a large skillet over medium-high heat. Add 3 tablespoons of the oil and sauté the onion for 10 minutes, until it starts to darken, then cook slowly over low heat for about 30 minutes, until it is dark brown and about half its original volume. Add the garlic, almonds, barberries, and tamarind, and cook over low heat until the mixture becomes fragrant, about 10 minutes. Stir in the herbs and season with salt and pepper. Let cool to room temperature.
Remove the fish from the refrigerator. Open each fish toward you, leaving the bottom flat against the pan. Spread the filling evenly from head to tail, then press the top half of the fish down firmly to cover the filling. Tuck any excess filling inside. Brush the fish with the remaining 2 tablespoons oil.
Bake for 12 to 15 minutes, until the top turns golden and the fish flakes easily. Serve with the lime wedges.
I'm fascinated by the way food connects us with different times, places, and each other. I live in Nashville, TN, a city rich with culinary traditions and a fast growing immigrant population. As Culinary Liaison for the Tennessee Immigrant and Refugee Rights Coalition, I organize events that unite people around food and spotlight the work of immigrant chefs. My cookbook The New Persian Kitchen is a winner of Food52's Piglet award. I love cooking Iranian rice and hearing people crunch on the crispy tahdig from the bottom of the pot. Find my Persian Rice Bonnet and Persian Spice Kit on my website and on Etsy.