Dice the chicken breast into even 1-inch pieces and season thoroughly with sea salt, black pepper, and dried thyme.
Heat the extra virgin olive oil in a large non-stick skillet over medium-high heat until shimmering.
Add the seasoned chicken to the skillet in a single layer and sear until golden brown and cooked through, approximately 5 to 7 minutes.
Transfer the cooked chicken to a clean plate and set aside.
In the same skillet, add the finely chopped yellow onion and sauté for 3 to 4 minutes until softened and translucent.
Stir in the minced garlic and cook for 60 seconds until the aroma is released.
Add the leftover cooked rice to the pan, using a spatula to break up any large clumps, and stir to coat the grains in the aromatics.
Return the chicken and any accumulated juices to the skillet, then add the fresh baby spinach, tossing gently until the leaves just begin to wilt.
Remove from heat and stir in the fresh chopped parsley and lemon juice to brighten the flavors before serving.