1. Heat a small skillet over medium heat and add the vegetables oil. Add the slivered almonds and stir them in the pan until they are golden brown.
2. In a medium bowl, whisk together the Dijon mustard, lemon juice and Sherry vinegar. Add the capers, caper juice and a pinch of salt and pepper. Slowly whisk in the olive oil. Taste for seasoning. Set aside.
3. Bring a large pot (enough to hold about 6 quarts of water) to a boil. Add salt until it tastes like mild seawater. How will you know? Take a little water with a spoon and taste a drop of it.
4. Prepare an ice bath by filling a bowl large enough to hold the green beans with cold water. Add some ice cubes and put a colander in the middle of the bowl. Stir the green beans into the boiling water and allow them to cook, 2-3 minutes. Use a slotted spoon to remove them from the water, transferring them immediately to the colander inside the ice bath. Allow them to sit in the ice bath for a few minutes, swirling them gently in the water to assure they are all cooling in the cold water.
5. Transfer the green beans to a kitchen towel spread on a flat surface and thoroughly dry them. Transfer them to a medium bowl. Season with salt and pepper to taste and toss with the vinaigrette and the toasted almonds. Serve immediately.