Place potatoes in medium-size saucepan and cover with cold water. Salt lightly. Bring to a boil and simmer 15-20 minutes until tender. Meanwhile, cook bacon in a large nonstick skillet until crisp. Remove to paper toweling. Add onion to drippings and cook 3 minutes. Add sliced steak and salt. Cook 2 more minutes until steak is no longer pink. Remove steak and onions to a plate and keep warm.
Add honey and vinegar to skillet; cook over medium heat 2 minutes. Add cornstarch mixture; cook for 30 seconds. Remove from heat.
Drain potatoes; run under cold water. Cut into quarters and place in bowl along with the crumbled bacon and steak-onion mixture. Add baby spinach, warm honey cider-vinegar dressing and tomatoes. Toss gently and serve.