Beef Sirloin Steak with Baby Spinach

I am trying to learn how to cook beef better since it often turns out tough or dry. I found this Campbell's  recipe and wanted to try it with a few little changes. This is the recipe as I made it. The beef was tender and I loved all the veggies. The sauce also is like a gravy for the mashed potatoes I made.

Beef Sirloin Steak with Baby Spinach
Marinade:
1/4 c. olive oil
2 T. lemon juice
2 t. fresh rosemary or 1 t. dried rosemary leaves 
1 lb. boneless beef sirloin steak, 3/4-inch thick, cut into 4 pieces 
Sauce:
2 T. olive oil
1 large onion, sliced (about 1 c.)
1 small red bell pepper, chopped (about 1/2 c.)
1/2 c. julienne carrots
3 cloves garlic, minced
1 can (10 3/4-oz.) condensed cream of mushroom soup
1 1/2 c .water
2 T. balsamic vinegar
1 T. chopped fresh rosemary leaves or 1 t. dried rosemary leaves, crushed
1 bag (about 7 oz.) fresh baby spinach

Mix marinade ingredients together. Add steak and toss to coat. Refrigerate for 4 hours.

Heat the 1 tablespoon oil in skillet. Add the onion, red pepper, and carrots and cook for 1 minute, stirring occasionally. Add the garlic and cook until the vegetables are tender-crisp, stirring often.

Stir the soup, water, vinegar and rosemary in the skillet and heat to a boil.  Stir in the spinach. Keep warm while cooking steak.

Heat 1 tablespoon oil in a 12-inch skillet over medium-high heat.  Add the beef and cook until well browned on both sides and just cooked to desired doneness in middle.  Remove the beef from the skillet.



Plate steak and pour sauce with vegetables on top.