Mix the chicken breast with the buttermilk, Worcestershire sauce and garlic. Cover and refrigerate for 4 hours or overnight.
Set oven to 220°C and line a baking tray with parchment paper.
Mix the flour, black pepper, smoked paprika, thyme and salt. Take chicken from marinade, roll in the flour mixture and place on parchment paper lined tray.
Brush the chicken with oil lightly and place in oven. Cook for about 20 minutes or until crispy and cooked through.
Mix all the ingredients together, season with salt and pepper to taste.
Cook the tortillas in a dry hot pan for a minute each side.
Mix the scallions into the sour cream.
Take a tortilla and spread a quarter of the sour cream in the middle. Scatter a quarter of the cheese, and top with a quarter of the crispy chicken. Spoon a quarter of the salsa on top and garnish with some fresh coriander if you wish.