Preheat oven to 375 degrees F.
Dice the chicken breasts into 1-inch cubes. Place the chicken cubes into a large bowl or ziploc bag.
Next, slice the red onion thinly and halve the cherry tomatoes. Add to the bowl or bag with the diced chicken.
Next, mix up the marinade in a small bowl. Pour over the chicken and veggies and give it a quick toss so that everything is coated.
At this point you can either place the mixture in the fridge to marinate for a bit (I like to make it in the morning and leave it for the day to let those flavours infuse).
If you’re really pressed for time, dump the mixture on a parchment paper-lined baking sheet and cook it right away for 25-30 minutes, flipping the chicken and veggies so that they get equal cooking on both sides.
Serve over a bed of rice or pita with a sprinkle of olives, feta cheese and side of tzatziki, if desired (or see additional serving options above).