Mix together the salt, sugar, paprika, garlic granules and oregano in a small bowl, put the chicken thighs into a baking dish, sprinkle over the salt-and-spice mix and rub into the chicken really well. Leave to marinate for 1 to 4 hours.
Heat the barbecue to medium high with the coals banked up one side, or with one of the gas burners on high with the others off (see Notes to oven cook). Put the chicken thighs, skin-side down, over the coals for 5 to 10 minutes or until golden and charred, then move to the indirect heat side and cook for another 35 to 40 minutes with a lid on, turning and moving every 5 minutes until cooked through.
Meanwhile, whisk the mayonnaise, soured cream, white wine vinegar, garlic granules, Worcestershire sauce, herbs and some seasoning in a bowl, then chill. Wedge the lettuce and chill.
Melt the butter in a small pan, fry the chopped garlic gently for 3 to 4 minutes or until it smells fragrant, then tip in the Frank’s or Tabasco sauce. Pour out into a large bowl. When the chicken is cooked, tip into the buffalo sauce and toss really well. Serve immediately with the wedged lettuce smothered in ranch dressing and sprinkled with chopped hazelnuts, and pickles on the side.