Soy protein isolate (SPI) has been used as an alternative protein source in texturized meat analogs due to its high protein content and health benefits. Twin-screw high-moisture extrusion was capable of texturing and shaping SPI into fibrous slabs similar to that of cooked skinless chicken breast yet harder and more rubbery due to significant post-extrusion moisture loss. The texture of extruded SPI was further optimized in the present study to reduce hardness and rubberiness. The combination of acetic acid treatment under pH 4.5 at 65°C for 50 min with addition of 0.1% (w/v) mixture of cornstarch and xanthan gum at a 3:2 (w/w) ratio yielded a tender SPI meat analog with desirable color closest to that of cooked skinless chicken breast. A novel vegetarian nugget based on the modified SPI meat analog was formulated and received consumer acceptance superior to commercial counterparts in its texture without detectable soy flavor.