For the blackened chicken: Combine all the spices with the garlic and oil in a bowl. Evenly rub the chicken pieces with the spice mixture. Place in a large re-sealable plastic bag or a bowl covered in plastic wrap. Keep in the refrigerator for 1 hour or up to overnight for a more intense flavor.
Preheat the oven to 350 degrees F.
In a cast-iron skillet heat over high heat, add enough vegetable oil to coat the whole bottom of the pan. The pan will be ready when it starts to gently smoke. First place the chicken drumsticks in the skillet (they take the longest to cook) and blacken all sides, about 5 minutes. Add the rest of the chicken pieces and continue in the same manner for another 5 to 7 minutes. Remove from the heat and place the skillet in the oven for 25 minutes. Remove from the oven, set aside and keep warm.
For the French vinaigrette: Add the tomato soup, ketchup, vinegar, honey, Worcestershire sauce, mustard seeds, shallot, garlic and lemon juice to a blender and puree all the ingredients together. Slowly add the oil until it emulsifies and becomes thick and creamy. Season with salt and pepper and blend again. (Add a little bit of water if the vinaigrette is too thick.) Store in a tightly covered container in the refrigerator. The vinaigrette can be made ahead and will be good for up to 1 week.
For the salad: In a bowl, mix together the romaine lettuce with the red onions, 2 tablespoons of olive oil and the red wine vinegar. Season with salt and pepper. Remove the chicken thighs from the skillet, slice lengthwise and toss into the salad. Mix well and set aside.
In another bowl, mix together the radishes, herbs and the remaining 1 tablespoon olive oil. Season with salt and pepper.
To serve: Dress the plates with the romaine and chicken thigh salad mix. Top each plate with a blackened chicken drumstick and garnish with the radish salad. Drizzle with the French vinaigrette and serve.