How to Make It
Preheat the oven to 350°. Spread the walnuts on a rimmed baking sheet and toast for 7 minutes, or until golden. Transfer to a plate and let cool. In a food processor, working in 2 batches, pulse the walnuts until coarsely chopped. Add the second batch of nuts back to the food processor and pulse in the 1/2 cup of olive oil. Do not overprocess: the pesto should be slightly chunky. Season with 2 teaspoons of salt and 1/2 teaspoon of pepper.
Transfer the pesto to a medium bowl. Mix in the goat cheese, shallots, watercress and lemon juice. Season with salt and pepper. Fold in the avocados. Drizzle the dip with olive oil and serve with radishes and assorted crisp vegetables.