Heat olive oil in a large skillet over medium-high heat.
Add chopped onion and cook for 2 minutes until it becomes clear.
Add corn, lima beans, green beans, red pepper, cherry tomatoes, garlic, smoked paprika, sage, salt, and black pepper. Add diced red chiles, if using. Cook, stirring occasionally, for about 5 to 6 minutes until vegetables are tender.
Stir in butter and parsley, and cook for 1 more minute until the butter melts. Taste and correct seasonings if needed.