As diets change in response to ethical, environmental, and health concerns surrounding meat consumption, fermentation has potential to improve the taste and nutritional qualities of plant-based foods. In this study, cauliflower, white beans, and a 50:50 cauliflower-white bean mixture were fermented using different strains of Lactobacillus plantarum. In all treatments containing cauliflower, the pH was reduced to <4 after 18 h, while treatments containing only white beans had an average pH of 4.8 after 18 h. Following fermentation, the riboflavin, folate, and vitamin B 12 content of the cauliflower-white bean mixture was measured, and compared against that of an unfermented control. The riboflavin and folate content of the mixture increased significantly after fermentation. Relative to control samples, riboflavin increased by 76-113%, to 91.6 ± 0.6 μg/100 g fresh weight, and folate increased by 32-60%, to 58.8 ± 2.0 μg/100 g fresh weight. For one bacterial strain, L. plantarum 299, a significant 66% increase in vitamin B 12 was observed, although the final amount (0.048 ± 0.013 μg/100 g fresh weight) was only a small fraction of recommended daily intake. Measurements of amino acid composition in the mixture revealed small increases in alanine, glycine, histidine, isoleucine, leucine, and valine in the fermented sample compared to the unfermented control.