Combine the peri-peri sauce, olive oil, sugar or honey, salt and pepper in a blender or use an immersion blender and blend until smooth and emulsified. This step is only necessary if the peri-peri sauce you are using is quite chunky.
Place the chicken thighs in a large bowl and pour over the marinade. Mix well to make sure the chicken is covered then cover with plastic and allow to marinate for at least 30 minutes but up to 24 hours in the fridge.
Soak large bamboo skewers in boiling water for at least 30 minutes. Alternatively, use metal skewers.
Thread the marinated chicken onto the soaked skewers.
Preheat a grill (or braai) on medium-high heat for 5-10 minutes.
Place the chicken espetada on the grill and cook for 7-10 minutes per side until well-browned and cooked through. If your grill has a lid, closing it will allow the chicken to cook faster.
Remove the chicken from the grill and allow to rest for 5 minutes before serving.