Combine lettuce and next 4 ingredients in a large bowl. Add lemon juice, olive oil, salt, and pepper; toss gently.
Spread 1 1/2 tablespoons hummus inside each pita half; spoon salad mixture evenly into halves. Serve immediately.
Make it Faster
To make this meal even faster, forgo rinsing, slicing, and chopping the fresh vegetables and fruit yourself. Look in the produce section for packaged torn romaine lettuce and containers of presliced red onion, prechopped cucumber, and prechopped mixed melon. Sometimes these items may be more expensive, but the trade-off is time saved from prepping and cleaning.