How to Make It
Cook pasta in a large pot of boiling salted water until al dente, 8 to 10 minutes; drain and rinse pasta under cold water to cool.
Meanwhile, combine olive oil, cilantro, lime juice, ½ of the avocado, ½ teaspoon of the salt, ¼ teaspoon of the pepper and ¼ cup of water in a blender and process until smooth, scraping down sides as needed.
Combine pasta and avocado dressing in a large bowl and toss to combine. Add beans, tomatoes, corn, and remaining ½ teaspoon salt and ¼ teaspoon pepper; toss well. Thinly slice remaining half of avocado. Serve salad topped with scallions and avocado.