Cook the tortellini according to package directions. Drain and set aside.
Soak the onions in a bowl of clean, cold water. Drain after 5 minutes.
In a large bowl add the onion slices, tomatoes, cucumber, pepper, cheese, and tortellini. Gently toss them together.
In a different bowl, whisk together the vinegar, lemon juice, sugar, oregano, and red pepper flakes. Slowly add the olive oil and whisk everything together until fully incorporated. Season with salt and pepper. Pour the dressing over the tortellini salad and gently mix until everything's nicely coated with the dressing. Serve this salad warm or at room temperature.
Notes
recipe adapted from Eats Well With Others Serving a crowd? No worries! The recipe easily doubles. Just don't cry any crocodile tears over the empty bowl that comes home and the fact that you have no leftovers to enjoy later on.