Prep the vegetables. Preheat your oven to 425°F (220°C). Chop broccoli, bell peppers, and zucchini into bite-size pieces.
Toss with olive oil, salt, and pepper. Spread on a sheet pan and roast for 18–22 minutes, turning halfway, until browned and tender.
Cook the grains. While the veggies roast, warm leftover rice or cook quinoa/farro according to package directions. Fluff and keep warm.
Season the steak. Pat the steak cubes dry with paper towels.
Toss with salt, pepper, smoked paprika, and 1 tablespoon olive oil. Dry surfaces sear better, so don’t skip this step.
Preheat the pan. Heat a large stainless steel or cast-iron skillet over medium-high until very hot. You should see a whisper of smoke when a drop of oil hits the pan.
Sear the steak. Add the steak in a single layer.
Don’t crowd the pan. Sear undisturbed for 1.5–2 minutes, then flip and cook another 1–2 minutes, until browned outside and medium-rare inside. Work in batches if needed.
Transfer to a bowl and tent with foil.
Make garlic butter. Reduce heat to medium-low. Add butter to the skillet. When melted and foamy, add garlic.
Stir for 30–45 seconds until fragrant, not browned. Stir in lemon juice and parsley. Taste and season with a pinch of salt if needed.
Coat the steak. Return the steak and any juices to the pan.
Toss in the garlic butter for 20–30 seconds to glaze. Remove from heat.
Assemble bowls. Add a scoop of grains to each bowl. Top with roasted vegetables and butter-glazed steak.
Add avocado slices and pickled onions or a squeeze of lime if using.
Finish and serve. Spoon any remaining garlic butter over the bowls. Crack fresh pepper on top and serve immediately.