Source: Martha Stewart, Everyday Food August 2007
adapted by http://theresalwaysthyme.blogspot.com/
note: I used frozen wax and green beans, already trimmed! and steam in the microwave!)
8 ounces green beans, stem ends removed, halved on the diagonal
4 ounces yellow wax beans, stem ends removed, halved on the diagonal
2 tablespoons Dijon mustard
2 tablespoons red-wine vinegar
2 tablespoons olive oil
Coarse salt and ground pepper
1 can (15 ounces) cannellini beans, rinsed and drained
1 chopped shallot
Fill a large bowl with ice water; set aside. Set a steamer basket in a large pot with a lid. Fill with a couple inches of water, enough to come just below basket; bring to a boil. or you can steam in the microwave.
Place green and wax beans in the steamer basket; reduce heat to a simmer. Cover pot, and steam until beans are crisp-tender, 6 to 8 minutes. With tongs or a slotted spoon, transfer beans to ice water. Drain, and pat dry.
In a medium bowl, whisk together shallots, mustard, vinegar, and oil; season with salt and pepper. Add all the beans; toss to coat. If storing, refrigerate up to 1 day; bring to room temperature before serving.