Preheat oven to 400 degrees F.
Place plum tomatoes in a shallow baking dish, drizzle with olive oil and scatter thyme sprigs over all. Season with salt and pepper. Roast until tomatoes are softened but still have their shape, about 15 to 20 minutes. Cover loosely with foil and set aside.
Reduce oven temperature to 350 degrees F.
Lay the salmon fillets skin side down with some space between them on a baking sheet or baking dish. Season with salt and pepper and cover with dill. Squeeze 1/2 of the lemon over all. Bake until firm, 15 to 20 minutes.
Meanwhile, slice the remaining lemon half into 1/4-inch slices. Heat a skillet over high heat. Film the bottom of the pan with olive oil and add lemon slices. Saute until brown on both sides, about 5 to 7 minutes total. Remove from heat and set aside.
Remove the aluminum foil from the tomatoes and discard the herb sprigs. Place the tomatoes on a cutting board and roughly chop.
Spoon chopped tomatoes into the center of each plate. Lay a piece of salmon over the tomatoes and lay the lemon halves to the side of the salmon. Serve immediately.