1 pound sirloin tip steaks , trimmed of excess fat and cut into 1/2-inch pieces (see note)
2 tablespoons soy sauce
1 teaspoon vegetable oil
1 pound cremini mushrooms , stems trimmed, caps wiped clean and quartered
1 large onion , chopped medium (about 1 1/2 cups)
2 tablespoons tomato paste
1 medium garlic clove , minced or pressed through a garlic press (about 1 teaspoon)
1/2 cup red wine
4 cups beef broth
1 3/4 cups low-sodium chicken broth
4 medium carrots , peeled and cut into 1/2-inch pieces (about 2 cups)
2 medium ribs celery , cut into 1/2-inch pieces (about 3/4 cup)
1 bay leaf
1 tablespoon unflavored gelatin (powdered)
1/2 cup cold water
2 tablespoons minced fresh parsley leaves
1. Combine beef and soy sauce in medium bowl; set aside for 15 minutes.
2. Heat oil in large Dutch oven over medium-high heat until just smoking. Add mushrooms and onion; cook, stirring frequently, until onion pieces are brown and dark bits form on pan bottom, 8 to 12 minutes. Transfer vegetables to bowl.
3. Add beef and cook, stirring occasionally, until liquid evaporates and meat starts to brown, 6 to 10 minutes. Add tomato paste and garlic; cook, stirring constantly, until aromatic, about 30 seconds. Add red wine, scraping bottom of pot with wooden spoon to loosen browned bits, and cook until syrupy, 1 to 2 minutes.
4. Add beef broth, chicken broth, carrots, celery, bay leaf, and browned mushrooms and onion; bring to boil. Reduce heat to low, cover, and simmer until vegetables and meat are tender, 25 to 30 minutes. While soup is simmering, sprinkle gelatin over cold water and let stand.
5. When soup is finished, turn off heat. Remove bay leaf. Add gelatin mixture and stir until completely dissolved. Stir in parsley; adjust seasonings with salt and pepper, and serve.
Choose whole sirloin tip steaks over ones that have been cut into small pieces for stir-fries. If sirloin tip steaks are unavailable, substitute blade or flank steak, removing any hard gristle or excess fat. Button mushrooms can be used in place of the cremini mushrooms, with some trade-off in flavor. If you like, add 1 cup of frozen peas, frozen corn, or frozen cut green beans during the last 5 minutes of cooking. For a heartier soup, add 10 ounces of red-skinned potatoes, cut into 1/2-inch pieces (2 cups), during the last 15 minutes of cooking.