Cook the rotini pasta according to package instructions; drain and rinse under cold water.
While pasta is cooking, cook the bacon in a skillet until crispy; then crumble it into pieces.
In a large bowl, combine the cooked pasta, crumbled bacon, halved cherry tomatoes, and chopped romaine lettuce.
In a small bowl, mix together the mayonnaise, lemon juice, salt, and pepper to make the dressing.
Pour the dressing over the pasta salad and toss to combine thoroughly.
Add sliced green onions and mix gently.
Taste and adjust seasoning if needed.
Cover and refrigerate the salad for at least 30 minutes to let the flavors meld.
Serve chilled or at room temperature.
Garnish with additional bacon or green onions if desired.