In a small bowl, cover the golden raisins with hot tap water and set aside. Place the potatoes in a medium pot and cover with cold water. Add 1 teaspoon of salt. Bring to a boil then reduce to a simmer and cook until the potatoes are fork tender but not falling apart, about 6-8 minutes. Meanwhile, place the shallots and garlic in a large bowl. Add 1 tablespoon of the Sherry vinegar and a pinch of salt and pepper. Once the potatoes are cooked, drain them and immediately add the hot potatoes to the bowl with the shallots and garlic; toss well. Drain the raisins and throw them into the bowl as well.
In a small bowl, whisk together the remaining 2 tablespoons of Sherry vinegar, grainy mustard, honey, 2 teaspoons of the chopped tarragon and the extra virgin olive oil. Season with salt and pepper.
Preheat a grill or grill pan to medium-high (alternatively, the chicken can be cooked in batches in a large skillet).
Brush the chicken breasts on both sides with a bit of oil, then season them with salt and pepper. Sprinkle the remaining 2 tablespoons of chopped tarragon evenly over both sides of the chicken breasts.
Lightly brush the grill with oil. Grill the chicken until golden on each side and cooked through, about 2-4 minutes per side.
To finish the salad, add the fennel, arugula, black olives and sliced almonds to the bowl with the potatoes. Toss with dressing to coat (you won’t need it all). Taste and season with salt and pepper.
To serve, place a chicken breast on each plate. Mound the salad over top. Crumble a nice amount of feta or goat cheese over each, and serve with additional dressing on the side.