For the tomato mint salsa: Combine the tomatoes, onion, mint, lemon juice and zest and paprika in a bowl. Mix with a spoon and season with salt.
For the coconut sauce: Heat the oil in a large skillet over medium-low heat. Add the garlic, paprika, turmeric, cumin and cardamom and cook until fragrant, about 2 minutes, stirring frequently. Stir in the tomato paste and cook for another minute. Add the coconut milk and whisk until well blended. Reduce the heat to low and simmer, covered, for 10 minutes. Season with salt.
For the scallops and prawns: On a shallow plate, combine the fenugreek leaves, oregano, garam masala, paprika, salt, pepper and garlic powder and mix well. Dip one side of each scallop into the spice mixture.
Heat the oil in a large skillet over medium-high heat. Cook the scallops, spice-side down until browned and crisp, about 3 minutes. Gently turn the scallops over and cook the other side until browned, about 3 minutes. Remove to a plate and set aside. Cook the shrimp in the same skillet until just cooked through, 2 to 3 minutes per side.
Line up four dinner plates and spoon a few tablespoons of the coconut sauce onto each plate. Place 3 scallops on top of the sauce on each plate and stack three shrimp on top of the scallops. Sprinkle the lime zest onto the plates. Spoon some tomato salsa onto each plate and serve immediately.