Preheat your oven to 400°F (200°C) to ensure a perfectly roasted outcome.

Prepare a large baking sheet by lining it with parchment paper or lightly greasing it with olive oil.

Arrange the broccolini, halved grape tomatoes, and quartered red onion on the baking sheet.

Drizzle the vegetables with olive oil and sprinkle with ground cumin, red-pepper flakes, kosher salt, and black pepper. Toss gently to coat evenly.

Place the lemon rounds on top of the tossed vegetables.

Roast in the preheated oven for about 20-25 minutes, or until the vegetables are tender and lightly charred.

Serve the roasted vegetables topped with slices of creamy feta cheese, alongside orzo or farro.