Blanch the haricots verts in salted boiling water until al dente (or cooked to your liking). Drain the beans into a strainer or colander and then they should be shocked by dunking the strainer of beans into a waiting bowl of ice water to stop the cooking process, and will help them retain a bright green color. Drain and set aside in refrigerator until needed.
Place the lime in a small microwave-safe bowl and microwave until the essential oils in the skin are released. The lime will be hot coming from the microwave, so let it cool just enough so you can handle it, before squeezing it. Turn on the blender and through the feed opening, add the rosemary, tarragon, cilantro, stone ground mustard, rice wine vinegar, and fresh ginger, and blend together until a smooth paste has formed. At this point the lime should be cool enough to squeeze. With the power on, add the lime juice through the blender feed-tube, and then very slowly add the oil and water until the mixture thickens and can coat the back of a spoon. Adjust the seasoning with salt and pepper. Set aside in refrigerator until needed. (When chilled, the dressing should resemble something like mayonnaise.) Reserve some of the dressing to drizzle on the plate later.
Then, mix the beans, onion, and tomato with the dressing (adjusting the amount to your preference) and refrigerate for only a couple of hours. (Don't mix too far ahead, because the salad ingredients will bleed and you will have a very runny dressing).