What is the test for requesting instructions on a defense if the evidence is substantial?

"Requested instructions on a defense must be given if they are supported by substantial evidence, rather than 'minimal and insubstantial' evidence. (People v. Flannel (1979) 25 Cal.3d 668, 684 [160 Cal.Rptr. 84, 603 P.2d 1].) Evidence is substantial if a reasonable jury could find the existence of the particular facts underlying the instruction. If the evidence is substantial, the trial court is not permitted to determine the credibility of witnesses, which is a task for the jury. [Citations.]" (People v. Lee (2005) 131 Cal.App.4th 1413, 1426.)