In a medium bowl, whisk together 1 tablespoon olive oil, lemon juice, oregano, minced garlic, salt, and pepper. Add the cubed chicken and toss to coat. Let marinate for at least 15 minutes.
In a small saucepan, combine rinsed quinoa and chicken broth. Bring to a boil, then reduce heat to low, cover, and simmer for 15 minutes or until liquid is absorbed. Remove from heat and let sit covered for 5 minutes before fluffing with a fork.
Heat the remaining 1 tablespoon of olive oil in a large skillet over medium-high heat. Add the chicken and cook for 8 to 10 minutes, turning occasionally, until the internal temperature reaches 74°C (165°F) and the exterior is golden brown.
Prepare the vegetable components by dicing the cucumber, halving the tomatoes, and slicing the red onion.
Divide the cooked quinoa equally into four serving bowls.
Distribute the grilled chicken, tomatoes, cucumber, red onion, and olives evenly across the bowls.
Top each bowl with 30g of tzatziki, 15g of hummus, and 25g of crumbled feta cheese.
Serve immediately or store in airtight containers for up to 4 days.