How to Make It
In a food processor, pulse the egg yolk with the buttermilk and garlic. With the machine on, drizzle in the olive oil until incorporated. Add the 3 tablespoons of cheese and the peppercorns and puree until smooth. Season the dressing with salt.
Bring a large pot of salted water to a boil. Fill a bowl with ice water. Boil the favas until just tender, 3 to 4 minutes. Using a slotted spoon, transfer the beans to the ice bath. Add the peas to the pot and cook until tender, 5 to 7 minutes for fresh and 1 minute for frozen. Drain and transfer to the ice bath. Drain the favas and peas. Pinch the fava beans out of their skins.
In a bowl, toss the favas, peas and greens. Add some dressing, season with salt and toss. Arrange the avocado on plates and top with the salad. Garnish with grated cheese and serve.