Preheat a grill to medium high. Grate the tomatoes on the large holes of a box grater into a medium bowl; discard the skins. Stir in 1/3 cup cilantro, the vinegar and ginger; season with salt and pepper. Set aside.
Spread the cauliflower florets on one half of a 24-inch-long piece of foil; sprinkle with 1/4 teaspoon garam masala and dot with the butter; season with salt and pepper. Fold the foil over the cauliflower and crimp the edges to seal and form a packet. Season the salmon with salt, pepper and the remaining 1 teaspoon garam masala.
Brush the grill grates with vegetable oil. Grill the foil packet on one side of the grill until the packet is puffed and the cauliflower is lightly charred and tender, about 6 minutes per side. Grill the salmon on the other side of the grill until opaque but still pink in the center, 3 to 4 minutes per side. Transfer to a large plate. Grill the naan until lightly toasted, about 1 minute per side; cut into wedges.
Carefully open the foil packet and toss the cauliflower with the remaining 2 tablespoons cilantro. Top the salmon with the tomato-ginger sauce and serve with the cauliflower and naan.