Roast the walnuts in a pan for 4 to 5 minutes. Crush them into small pieces.
In a bowl, stir well the oil, vinegars, and coffee. You want to create an emulsion. Add salt and pepper.
Slice the pears using a mandolin and nicely set them on the plates.
Divide nuts and blue cheese between the plates. Add a couple of tablespoons of dressing to each plate, sprinkle some fresh thyme and serve immediately.