In a large pot of salted boiling water, cook the green beans until tender, 2 to 3 minutes. Drain in a colander and rinse with cold water to stop the cooking. Set aside.

For the vinaigrette: In a small bowl, whisk together the lemon juice, vinegar, mustard, and sugar. Gradually whisk in the olive oil until emulsified. Season with salt and pepper to taste.

Transfer the green beans to a serving bowl. Add the onion and vinaigrette. Toss to coat evenly. Season with salt and pepper to taste. Divide among small plates. Sprinkle each with an equal amount of the blue cheese and almonds and serve.

Note: To toast nuts, preheat the oven to 350°F. Spread the nuts on a sided baking sheet and bake until aromatic, following the time chart below for each type of nut. Be careful not to burn the nuts, as most have a high oil content that makes them toast quickly and burn easily.

Almonds: 7 to 10 minutes for whole, about 5 minutes for sliced
Pecans: 5 to 7 minutes
Pine nuts: 5 to 7 minutes
Walnuts: 7 to 10 minutes