Preheat the oven to 450 degrees and place the oven racks in upper and lower thirds. Toss the rhubarb gently with the raw sugar and honey and then evenly distribute them on a baking sheet. Roast them on the upper rack until the rhubarb softens slightly and becomes fragrant, about 5 minutes. Remove from the oven and allow to cool on the baking sheet. On another rimmed baking sheet, toast the mixed nuts on the lower rack until aromatic, about 5 minutes. Let cool, then crush them slightly (I usually put them in a ziplock bag and then pound it with a meat tenderizer for a few beats) and toss with a pinch of salt. Set them aside.