According to global recommendations, quality diets for complementary feeding (CF) should include a diversity of foods including vitamin A-rich fruits and vegetables and sources of high-quality proteins and essential nutrients, particularly animal-source foods (ASF). A key barrier to feeding ASF surrounds beliefs that the preparation of foods of a thicker consistency may cause problems of digestion, “heaviness” or stomach problems, swallowing, and choking. The objective of this study was to explore, through systematic formative research, the acceptability, use, and feasibility of a simple technology, commercial infant food grinders, in two rural Peruvian settings where there is delayed and low consumption of complementary foods of a thick consistency, including ASF. Phase I explored the barriers, constraints, and opportunities related to the provision of foods of a thicker consistency with a focus on ASF. Phase II encompassed household behavioural trials with mothers and infants to assess the acceptability and use of the grinders in the home setting, using key concepts and messages developed from the information obtained during Phase I. The technology was highly acceptable, used by the majority of mothers (87.8%), and led to changes in cultural perceptions, facilitating increased feeding of appropriate textures (thick purees), ASF, and multimicronutrient powders. Energy, protein, and micronutrient intakes were all significantly greater after the household behavioural trials. This simple technology, paired with systematic formative research to appropriately promote its use across cultures, may have a significant effect on improving CF practices globally, particularly for young infants beginning CF at 6 months.