In the bottom of a large salad bowl, mix together the Dijon mustard, lemon juice, and pesto. Add the greens and toss to coat. Add the fennel, radishes, avocado, and walnuts. Season to taste, adding more pesto, lemon, salt, and pepper to taste.
*You can use any salad greens here. If you use kale, either chop it small or lightly massage it with ½ teaspoon of olive oil before adding it to the salad bowl.