Steam the broccoli and set aside covered in a warm place. Then begin steaming the asparagus until fork tender, remove from heat and keep warm.
While the broccoli and asparagus are steaming, heat the olive oil and butter in a large skillet over medium heat.. Saute the onion until translucent and add the carrots. When the carrots begin to soften, add the red bell pepper, parsley and tarragon and continue cooking until the bell pepper is tender. Fold in green beans. Season with cayenne pepper and salt.
Arrange asparagus and broccoli on serving dish and spoon rest of vegetable mixture over.