Thoroughly wash the spinach several times under running water (since it grows close to the ground, it is often very dirty). Drain thoroughly onto a cloth. Into a small jar, add the balsamic vinegar, olive oil, honey, cranberry jam and a pinch of salt. Close the lid tightly and shake thoroughly until the mixture emulsifies and becomes light and foamy. Thinly slice the goat cheese (with a cheese or vegetable slicer). Arrange the spinach in a big salad bowl with the goat cheese and grapes on top. Pour the dressing over. This hearty salad is reminiscent of autumn, but it can be a heavenly dinner by adding a thinly sliced roasted duck breast to it.