Rinse the green beans and pat dry. Trim the ends from the green beans by lining up several in a row and then cutting the ends off all at once.
Place green beans, red onion, sliced garlic, and halved tomatoes on a sheet pan and spread into a single layer. Do not overcrowd.
Drizzle olive oil over the top of the vegetables.
Sprinkle generously with salt, pepper, and a pinch of red pepper flakes.
Toss the vegetables to distribute the oil and seasonings.
Roast for about 14 minutes or until the vegetables are beginning to caramelize.
Serve immediately
Video
Notes
Don’t overcrowd the vegetables on the sheet pan. You can divide the vegetables between two sheet pans if you’d like. Ample space on the sheet pan allows for more caramelization, which is what makes this dish so delicious.You can also add 1/2 teaspoon of Italian seasoning to the vegetables.These have some spice. For more mild green beans, omit the red pepper flakes. I used about ½ teaspoon each salt and pepper. Adjust for your own personal preference.