Make the marinade: In a bowl, whisk olive oil, lemon zest and juice, garlic, rosemary, thyme, oregano, salt, pepper, and red pepper flakes.
Marinate the steak: Pat the steak dry. Place it in a zip-top bag or shallow dish, pour in the marinade, and coat well.
Refrigerate for at least 30 minutes, up to 8 hours.
Cook your base: Prepare quinoa, farro, or brown rice according to package directions. Fluff and set aside.
Prep the veggies: Halve tomatoes, dice cucumber, slice red onion, and chop herbs. Keep everything ready for quick assembly.
Make the drizzle: Whisk olive oil, lemon juice, Dijon, honey, herbs, salt, and pepper until emulsified.
Cook the steak: Heat a cast-iron skillet or grill over medium-high.
Remove steak from marinade, letting excess drip off. Sear 3–5 minutes per side for medium-rare (time varies by thickness). Use a thermometer for accuracy: 125–130°F for medium-rare, 135°F for medium.
Rest and slice: Transfer steak to a cutting board and rest 5–10 minutes.
Slice against the grain into thin strips for tenderness.
Assemble the bowls: Add grains and greens to each bowl. Top with steak, tomatoes, cucumber, red onion, and avocado. Sprinkle herbs and any add-ons.
Drizzle with the lemon herb sauce.
Taste and adjust: Add a pinch of salt, extra lemon, or more drizzle if needed. Serve warm or at room temperature.