Rub salmon fillets with 1/2 teaspoon salt and turmeric; cover and refrigerate 5 minutes. Heat 1 teaspoon oil in a large nonstick skillet over medium-high heat. Add fillets; cook 1 minute on each side. Remove fillets; cover and set aside. (Fish need not be fully cooked.)
Combine 2 teaspoons oil and Panch Phoron Blend in pan; cover and cook for 30 seconds, shaking pan constantly. Add onion and potato; stir-fry for 6 minutes or until vegetables begin to brown, stirring frequently.
Place 1 pound tomatoes in a food processor; process until pureed. Add 1/2 teaspoon salt, tomato puree, zucchini, and the next 4 ingredients (zucchini through garlic) to pan; bring to a boil. Cover, reduce heat, and simmer 10 minutes or until vegetables are tender. Stir in yogurt until well blended.
Return the fillets to the pan, carefully nestling them into the vegetable mixture. Arrange the chiles and tomato wedges on top of the vegetable mixture; cover and cook 20 minutes or until fish flakes easily when tested with a fork. Sprinkle with Garam Masala and cilantro.