The serverless computing paradigm has emerged as a promising solution to address the resource underutilization and inflexible service scaling in edge environments by decoupling the monolithic application into a serverless workflow. However, existing serverless platforms are primarily designed for cloud centers, relying on heavyweight isolation mechanisms that are illsuited for resource-constrained edge computing. These limitations result in high latency, low deployment density, and restricted parallelism. In this paper, we proposeSonnet, a serverless platform tailored for edge computing, capable of rapidly responding to user requests and supporting efficient and elastic service scaling. Sonnet offers these features by (i) employing lightweight WebAssembly as the execution environment for functions, (ii) leveraging serverless workflow information to optimize function deployment on resource-constrained edge environments, and (iii) designing a function deployment algorithm that achieves dynamic load balancing within the cluster. An extensive evaluation ofSonnetwith real-world serverless workflows demonstrates its effectiveness and practical applicability. Compared with SOTA and commonly used edge computing serverless solutions, our experiments show that Sonnet can reduce end-to-end latency by 27% and improve throughput by 2.83×.