In a large bowl, oil, tomato, scallions, walnuts, parsley, pepper, and salt. Let sit for 30 minutes, or up to 4 hours. Cover and chill if longer than 1 hour, but bring to room temperature before proceeding.
Bring a large pot of water to a boil. Drop in the ravioli and cook until tender but still slightly firm, about 5 minutes. Drain thoroughly in a colander.
Toss the ravioli with the tomato mixture. Sprinkle on the blue cheese and gently toss again. Serve warm, not piping hot.