In a large bowl, add the olive oil, lemon juice, lemon zest, black pepper, garlic powder, onion powder, and salt and whisk to combine.
Add the chicken thighs to the bowl and toss in the marinade to ensure that they are well coated. Transfer the bowl to the fridge and allow to marinate for at least 15 minutes or up to 8 hours. If time does not permit, you can grill the chicken thighs right away, you just won’t get the same depth of flavour.
When the chicken is ready, preheat a grill or grill pan to medium-high heat.
Add the chicken thighs to the grill and cook for 4-5 minutes per side, turning once, or until the internal temperature of the thickest part of the thigh reaches 165°F.
Once cooked, remove the chicken thighs from the grill, transfer to a plate, and allow to rest for 5 minutes before serving to help preserve the juices.
The chicken thighs can be served immediately or stored in an airtight container in the fridge for up to 4 days.