either your grills not hot enough for your steak or you turned your steak too early.. theres not enough sear on them, but those prawns look goooooood!!
i hate to see good food not cooked to perfection.. so heres some tips
id grill the steaks and tomatoes together then grill the prawns on around med-heat for about 3-5 minutes on each side after because they all require different temps.
Heat up the grill and if you have two burners, make one side the hottest and the other side cool (smallest flame).. put steak on hot side for about 2 minutes per side and tomatoes on cooler side (or hot depending on how you want them cooked), then when steak is seared on both sides transfer them to the cooler side - usually around another 1-4 minute per side depending on thickness and desired doneness.
I usually use the finger test to see how rare my steak is:
http://barbecuetricks.com/steak-done...-handy-method/
but anywho last thing i grilled was 14oz ribsteaks with red peppers and zuchinni on the side.. unless im feeling fancy, i usually only use salt and pepper to season everything and let the grill do the work!