Preheat oven to 350°F
Clean your chicken, then cut it into 2" pieces and place in a ziplock bag. Refrigerate until time to use.
In a small dish, mix all your seasonings. Roughly cut your two peppers and yellow onion, tossing them in the olive oil. Sprinkle the seasoning mix over the peppers and onion. Place them on a sheet pan and roast for 20 minutes.
After twenty minutes, remove from oven and mix around, tossing in the garlic cloves. Roast for another 10 minutes.
Remove the vegetables from oven and let them cool slightly. Add the vegetables to a blender and blend until a paste forms. This shouldn't be too thick or too runny. Add a little more olive oil if needed.
When marinade has completely cooled, add it to the ziplock bag with the chicken. Add the lemon juice to the bag as well. Mix the chicken and the marinade until evenly coated and place back in fridge for 2-24hrs.