For the dressing: Combine the buttermilk, yogurt and ranch mix in a small bowl and whisk together.
For the salad: Place the eggs in a small saucepan and fill with cold water; bring to a boil. Immediately remove from the heat and cover the pot for 10 minutes. Drain the eggs and submerge in an ice bath for 5 minutes. Peel and set aside.
Lay the chicken flat on a cutting board and slice each breast in half horizontally. Sprinkle with the salt and pepper, then rub the chicken with the oil on all sides. Cook the chicken on a grill pan or grill set to high heat, about 5 minutes per side.
Place the bacon strips on a paper-towel-lined microwave-safe plate. Place another paper towel on top of the bacon and microwave for 5 minutes on high heat.
Dice the chicken, eggs and bacon. Toss the kale with half of the dressing, then arrange on the serving plates. Divide the chicken, eggs, bacon, onions, avocados and tomatoes in clusters or lines among the plates. Drizzle the remaining dressing over the top or serve the dressing on the side.