Lunch in Irwindale
I was about to suggest Il Forno, but alas it shut down last week:
So, I'd head just a mile or so west to Tacos Ensenada (Huntington just west of Mt. Olive in Duarte) for the superb shrimp and fish tacos; the best I've had in the SGV. Other seafood dishes there are good, too, but the non-seafood tacos are merely OK.
Even better is Market Grill in Monrovia (Colorado & Shamrock); their club sandwich with homemade lemon/mint potato salad on the side just puts others to shame. Everything else is good, too (especially the burgers, veggie sandwich, bacon chocolate chip cookies, and soup specials) and made from scratch - they hand-grind the steak for burgers in front of you - so I'd highly recommend calling in your order in advance so you can make it back within the hour.
The Market Grill
525 S Shamrock Ave, Monrovia, CA 91016