Preheat the oven to 425 degrees and prepare a baking sheet with parchment paper or a silicone mat.
Cut vegetables into similar sizes so they cook evenly. Leave the tomatoes whole.
Place vegetables onto the baking sheet in a single layer.
Season with garlic, Italian seasoning, cumin, and red pepper flakes.
Roast for 30 minutes.
Put vegetable broth and plant milk in a large blender cup.
Transfer half the roasted vegetables to the blender and reserve the rest for a chunky soup.
Or, add all roasted vegetables for a pureed soup.
If using a smaller blender, batch blend and transfer blended soup to a pan to heat.
Transfer blended soup to a pan to heat if your blender does not have a heating element.
Garnish with reserved diced bel peppers, green onions, and parsley.