I am a burger purist. nothing goes inside the meat apart from salt, 1% of the weight of meat. Form the putty rub with sunflower oil (to withstand high heat) and heat your pan until it is scorching hot. place putty on pan and flip every 20-30 secs. For puttys of 1.5-2cm thickness that I usuall do, it should take about 6-7 mins until core temperature reaches 65-67C. USE A PROBE! remove and cover with tinfoil for 5mins, they will reach 70C in the meantime. sorry but anyting above 70C is impossible to be kept juicy, unless it has a lot of fat in it... I cannot eat more that 15% fat burgers. the above method is the one the Heston recommends in his Perfection series for burgers, but I have been doing it for years (my greek granny was always doing that with meats she cooked! ). My girfriend hates pink meat, but she loves my burgers, although welldone they are very juicy. Even her hot headed Serbian dad conceeded! one addition: I usually have some lard or basting fat in the freezer. I melt it and then brush it on the cooked burger. I then put the burger in the extremely hot pan for 15sec each side (I use a la crouchete griddle pan) the lard has a low cooking point, and generate huge amounts of smoke, which however gives the burger an amazing smokey charcoal taste.