We propose a new design approach for systems-on-chip. The goal of the proposed design approach is to minimize the overall energy consumption dynamically, during runtime. The proposed approach builds on the well known globally asynchronous locally synchronous design style. To minimize power noise and losses, we propose to use a single high-voltage global power delivery network. Locally integrated DC-DC regulators generate a discrete range of supply voltage levels. These regulators are dynamically controlled by novel minimum energy point tracking (MEPT) controllers. The goal of the MEPT controllers is to seek in a decentralized fashion the minimum energy consumption point of each voltage frequency island via dynamic voltage and frequency scaling, thereby driving the entire SoC toward minimum energy consumption. Since the proposed MEPT controller relies on the extremum-seeking control theory, its stability is theoretically guaranteed. While the scope of this project is to address all design aspects of the proposed design style, in this paper, our contribution is to introduce and discuss the MEPT controller. Simulation results demonstrate its operation.