In a large Dutch oven, heat olive oil over medium heat. Add green onion, garlic, ginger, salt, black pepper, and red pepper; cook until soft.
Add collards and mustard greens and stir to combine. Increase heat to medium-high, add vegetable broth, and bring to a boil. Reduce to a simmer and cook until greens are tender, 30 to 40 minutes.
Add squash and cook until just tender, 15 to 25 minutes. Remove from heat, add vinegar, and stir to combine. Garnish with green onions, if desired.
Recipe by Taste of the South at https://tasteofthesouthmagazine.com/braised-squash-collards/