Make the marinade. In a bowl, whisk olive oil, lemon zest, lemon juice, garlic, Dijon, salt, pepper, oregano, basil, thyme, and red pepper flakes.
Marinate the chicken. Add chicken to the bowl or a zip-top bag and coat well. Marinate for at least 20 minutes at room temp or up to 4 hours in the fridge.
Longer than that can make the chicken mushy because of the acid.
Cook the grains. While the chicken marinates, cook your choice of grains according to package directions. Fluff and set aside.
Prep the veggies. Dice cucumber, halve tomatoes, slice red onion, and chop herbs. Set aside in small bowls for easy assembly.
Cook the chicken. Heat a large skillet or grill pan over medium-high.
Add a light drizzle of oil. Cook chicken 4–6 minutes per side, depending on thickness, until golden and the internal temperature reaches 165°F (74°C). Rest for 5 minutes, then slice.
Make the drizzle. Whisk olive oil, lemon juice, honey, herbs, salt, and pepper.
Taste and adjust acidity or sweetness as needed.
Assemble the bowls. Add a scoop of grains to each bowl. Top with sliced chicken, cucumber, tomatoes, red onion, fresh herbs, avocado, and feta. Finish with the lemon herb drizzle and extra lemon wedges.
Serve. Enjoy warm or at room temperature.
It also tastes great chilled for a packed lunch.