In a medium skillet, heat oil over medium-high heat. Add onion, bell pepper, garlic, and olives. Cook until tender, about 5 minutes.
Add in ground beef, using a spoon to break up the meat as it browns.
Stir in tomato paste and turn heat down to medium-low, stir for 2 minutes.
Add water and frozen peas and carrots, cover until just cooked through, about 4 minutes.
Stir in fish sauce (optional - but it is that *special secret ingredient* that adds a savory punch that makes people say "OMG why can't I stop eating this")
Stir in cilantro, salt, and pepper.
Serve over rice.