In the global supply chain, ensuring the integrity and safety of sensitive products, such as vaccines, is paramount. This paper introduces a concrete and novel framework for product provenance and supply chain monitoring that leverages Internet of Things (IoT) sensors and blockchain technology to address these challenges. The proposed framework employs IoT sensors to continuously monitor and record in an efficient manner the keeping conditions of products during transit and storage. The blockchain solution implied is an Ethereum-based open-source client, our framework making use of smart contracts. Targeted measurements are temperature and humidity levels, but the framework is not limited to those. These data, along with comprehensive product provenance information, are securely and transparently logged on a public blockchain, enabling end-to-end traceability and verifiability. Furthermore, any third-party application is able to access this information for all stakeholders, including end users, who can verify the authenticity and handling conditions of their products in a trustful manner. Although integrating IoT and blockchain technologies pose significant challenges, our proposed framework finds a good balance between the two. Our initial evaluation demonstrates the framework's effectiveness in providing a trustworthy record-keeping and accessible monitoring for supply chain in the current digital era.