Arugula with Pecorino Romano and Toasted Walnuts

For the dressing:
Combine 1½ TBS sherry or tarragon vinegar, 1-2 fresh garlic cloves finely chopped and ¼ tsp. salt.
-Whisk together and let stand for 15 minutes.
-Stir in 1 tsp Dijon mustard and 6 TBS of walnut/and or extra-virgin olive oil. 
For the greens: Without undoing the rubber band, gently swish 1-2 bunches of arugula in some cold water, and then shake dry. 
-Beginning from the top of the bunch of arugula, cut ½ inch strips off until you reach the bottom 2 inches and then discard the stems. 
-Gently spin the arugula dry in a salad spinner. 
-Chop up  1 TBS chives into thin slivers. 
-Put 1 tsp of butter in a small skillet over low heat.
-Add ½ cup walnut halves and toast until golden brown, 2-4 minutes. 
-Coarsely grate ½ cup Pecorino Romano.
To assemble salad: Gently toss the arugula with the chopped chives, enough dressing to coat and a little salt. 
-Heap on individual serving plates and top with a generous sprinkle of cheese and some walnuts.