The recommended approach for optimizing a Spark job with a large dataset and many features is to utilize the broadcast hint for smaller DataFrames in join operations. Broadcast joins can significantly reduce memory usage when joining a large DataFrame with a smaller one by broadcasting the smaller DataFrame to all cluster nodes, thus avoiding the need to shuffle large amounts of data across the network. This reduces memory pressure on individual nodes and improves overall performance. While other options like increasing executor memory or enabling automatic schema inference can play a role in optimization, they may not address the specific challenges of handling large datasets with many features as effectively as broadcasting smaller DataFrames in join operations.