Bring a pot of salted water to a boil. Add udon, and cook until al dente. Drain, and rinse. Drizzle with just enough sesame oil to coat. Spread on a baking sheet, and refrigerate 10 minutes.
Combine sesame oil, soy sauce, grapeseed oil, vinegar, chili sauce, and juice.
Divide udon among bowls. Top with crabmeat, cucumber, sprouts, and sesame seeds. Drizzle with dressing.