  Using the universal torsor method due to Salberger, we study the
approximation of a general fixed point by rational points on split toric
varieties. We prove that under certain geometric hypothesis the best
approximations (in the sense of McKinnon-Roth's work) can be achieved on
rational curves passing through the fixed point of minimal degree, confirming a
conjecture of McKinnon. These curves correspond, according to Batyrev's
terminology, to the centred primitive collections of the fan.
