Cut the tomatoes, scallions, cucumber, and onion in large pieces and place them in a food processor fitted with the steel blade. Add the garlic and pulse until the soup is coarsely pureed. Place it in a large bowl and whisk in the vinegar, olive oil, celery salt, red pepper flakes, tomato paste, tomato juice, 1 tablespoon salt, and 1 1/2 teaspoons pepper. Cover with plastic wrap and chill for 4 hours or overnight.
When ready to serve, preheat the broiler and place the top rack 5 to 7 inches from the heat. Cut 6 (1/2-inch-thick) diagonal slices from the baguette. Place on a sheet pan, brush with olive oil, and broil for 1 to 2 minutes on one side. Turn the slices, spread with the goat cheese, and broil for another minute, until the cheese is warm and the bread is toasted. Serve big bowls of cold soup with a warm goat cheese crouton and a drizzle of olive oil.