Make the Dressing: In a large bowl, whisk together the Greek yogurt, mayonnaise, Dijon mustard, salt, and pepper until smooth.
Make the Salad: To the same bowl, add the grapes, celery, and red onion, stirring to combine. Add the chicken and almonds, and toss gently until everything is evenly coated.
Taste and Chill: Taste and adjust seasoning if needed. Serve immediately or chill for 30 minutes or overnight for the flavors to combine.
Notes
Yogurt: I’ve tested this with both whole milk and low-fat Greek yogurt. The whole milk version adds a little extra richness, while the low-fat gives you a lighter texture and a bit more protein. Both work great, so just go with whatever you have or prefer. Nutrition information calculated with low-fat.
Mayo: Feel free to adjust the yogurt-to-mayo ratio depending on your preferences. More yogurt for a lighter feel, more mayo if you want it extra creamy.