In a large pot or deep skillet, heat the olive oil over medium heat.
Add the chopped onion and minced garlic, and sauté for 3-4 minutes until the onion becomes translucent.
Add the sliced red and yellow bell peppers to the pot and cook for another 3 minutes, stirring occasionally.
Pour in the vegetable broth and water, then add the dried penne pasta, dried oregano, salt, and black pepper.
Bring the mixture to a boil, then reduce the heat to medium-low and simmer uncovered.
Cook for about 10 minutes, stirring occasionally to prevent sticking.
Five minutes before the pasta is done, stir in the thawed green peas.
Continue cooking until the pasta is tender and most of the liquid is absorbed.
Remove the pot from heat and stir in the grated Parmesan cheese and chopped fresh parsley.
Taste and adjust seasoning if necessary, then serve immediately.