Nowadays, consumers have growing expectations for healthier and higher-quality food, and sustainable food choices are also taking on an increasingly central role. This paper assesses the environmental loads and energy resources of vegan, semi-vegetarian, and traditional restaurant soups and main dishes, focusing on preparation and cooking phases based on the life cycle assessment. The optimal menu samples were selected based on statistical methods. Mann-Whitney and Krus-kal-Wallis tests were applied to investigate restaurant products' distribution and carbon footprint. Based on the results, the preparation phases have a more significant impact. The environmental loads for the life cycle of vegan and semi-vegetarian menus are lower. Furthermore, a sustainability assessment model was developed by integrating lean and life cycle assessment approaches called "GreenCycLEAN." Research results are helpful for the sustainability of catering establishments.