Abstract: A integrally-formed knife for producing thick waffle-cut and lattice-cut potato slices has a blade and a shank extending rearwardly from the blade. The blade has opposing inclined surfaces which meet at a forward blade portion to define a thin corrugated cutting edge. Each blade surface has undulations defining a set of alternating grooves and ridges each extending rearwardly from the cutting edge and terminating at the shank. The relative inclination of the blade surfaces results in progressively greater blade thickness at a rear blade portion such that the blade is relatively rigid and self-supporting. This eliminates use of clamps on the opposing blade faces and consequent interference by clamps with slicing. The sets of grooves diverge relative to one another adjacent the rear blade portion where their bottoms are spaced in a direction transverse to the blade surfaces. The shank is unobtrusively connected to the relatively wide rear blade portion between the bottoms of rearward ends of the grooves.