Cut steak into bite-sized cubes carefully.
Pat shrimp dry with a paper towel.
In a bowl, add oil and lemon juice.
Add garlic, onion powder, paprika, oregano, salt, pepper.
Toss steak and shrimp in the marinade.
Cover and let marinate for 20 minutes minimum.
Preheat grill to medium-high heat until hot.
Thread steak, shrimp, peppers, onion onto skewers alternately.
Brush kabobs with remaining marinade evenly.
Place kabobs on the grill carefully.
Grill kabobs for 2-3 minutes on each side.
Ensure steak is cooked to desired doneness.
Shrimp should turn pink and firm up.
Remove kabobs from the grill gently.
Garnish with fresh parsley before serving hot.