In a 6-quart stockpot, warm the oil over medium-high heat.
Add the onion and cook, stirring often, until softened, about 4 minutes.
Add the garlic and a very generous pinch of red pepper flakes and cook, stirring constantly, for 30 seconds.
Add the peas and their juices to the stockpot and stir to combine.
Add the vegetable broth and salt, and bring to a boil.
Add the elbow pasta, and cook, stirring often, until al dente, about 7 minutes.
Remove from the heat, add the cheese and stir to combine.
Season with salt, to taste.
Serve immediately with some additional grated pecorino.