In a small bowl, whisk together mustard, large pinch of salt, large pinch of pepper, and the sugar. Add vinegar, and whisk to combine. While whisking, drizzle in oil. Continue whisking until emulsified. Add blue cheese, and stir gently to combine.
In a large bowl add endive and pomegranate seeds. Drizzle with dressing and toss to combine. Serve immediately.