Spring Chicken Dinner Salad

Name: Spring Chicken Dinner Salad
Ingredients: 2 large skinless, boneless chicken breasts (about 1¼ lb. total); 3 Tbsp. Diamond Crystal or 3½ tsp. Morton kosher salt, plus more; 1 lemon, halved; 2 Tbsp. Dijon mustard; 6 Tbsp. extra-virgin olive oil; Freshly ground black pepper; 8 oz. green beans, trimmed; 1 large head of Bibb lettuce; 1 small bunch chives, sliced into (2”-long) pieces; 1 cup basil leaves; 1 bunch radishes, trimmed, halved, cut into wedges if large; 1 cup torn peperoncini; 1 avocado, thinly sliced