Whisk together the dressing ingredients, taste and adjust to your liking. Set aside.
Salad
Thinly slice fennel into a small bowl (using a mandoline or grater). Drizzle a tiny bit of olive oil, and a small squeeze of lemon, with a sprinkle some salt. Toss and set aside for five minutes. (I find that marinating the fennel helps it become more tender).
Slice the pear thinly and coat with a squeeze of lemon, set aside.
Toast the walnuts.
Putting it Together
In a larger bowl, toss together the pears, arugula, fennel, half of the feta, walnuts and salad dressing.
Assemble on a platter and topped with the remaining feta, walnuts, mint leaves. Serve with more salad dressing on the side.