Meatball Soup With Beef Stew Vibes

Name: Meatball Soup With Beef Stew Vibes
Ingredients: 1 large egg; 4 garlic cloves, finely grated; 1 cup panko; 4 Tbsp. extra-virgin olive oil, divided; 1 Tbsp. thyme leaves; 3 tsp. Diamond Crystal or 1¾ tsp. Morton kosher salt, divided; Freshly ground black pepper; 1 lb. ground beef; 1 (packed) cup frozen, thawed pearl onions; 10 oz. mushrooms (any kind), torn into bite-size pieces; 2 Tbsp. double-concentrated tomato paste; 1 Tbsp. all-purpose flour; ⅔ cup dry red wine; 1 lb. Yukon Gold potatoes (about 4 medium), peeled, cut into 1 pieces; 4 cups low-sodium beef broth; ½ cup frozen peas; Country-style bread (for serving; optional)