Beef Medallions with Spring Mashed Potatoes recipes

Name: Beef Medallions with Spring Mashed Potatoes recipes
Ingredients: 1 1/2 lb. Yukon Gold potatoes, peeled and cut into 1-inch pieces; 1 tsp. coarse kosher salt, plus more, to taste; 3 Tbs. olive oil; 1/2 head small savoy cabbage, cored and thinly sliced crosswise; freshly ground pepper; 2 Tbs. unsalted butter; fat; 1 1/4 lb. beef tri-tip roast, excess fat trimmed; 2 large shallots, halved lengthwise and thinly sliced crosswise; 1 Tbs. all-purpose flour; 2 cups low-sodium beef broth; 2 Tbs. dry vermouth; 2 tsp. Dijon mustard; 1 1/2 Tbs. minced fresh thyme, plus more for garnish