Preheat the oven to 200 degrees. Scrub the sweet potato clean and cut it, unpeeled, into three-centimeter chunks. Toss them with one tablespoon of olive oil, salt, and pepper, and roast on a large baking sheet for fifteen minutes.
Meanwhile, cut the broccoli into florets and peel and slice the stem; it is just as delicious as the florets. Toss the broccoli with one tablespoon of olive oil, the crushed garlic, chili flakes, salt, and pepper.
After the first fifteen minutes, add the broccoli to the baking sheet with the sweet potato and roast everything together for another ten minutes.
Pat the salmon fillet dry, rub it with the remaining olive oil, salt, and pepper, and place it among the vegetables. Roast everything for another twelve to fourteen minutes, until the salmon is just cooked through and easily flakes into shiny layers under light pressure. The fish is intentionally added last: salmon is at its best at an internal temperature of around fifty degrees, and leaving it in for the entire roasting time results in dry, pale fish alongside perfectly roasted vegetables.
For the sauce, whisk the yogurt until smooth with the mustard, one tablespoon of lemon juice, plenty of finely chopped dill, salt, and pepper. Toast the pine nuts in a dry pan until golden brown.
Serve the salmon with the vegetables, spoon the dill yogurt alongside, and garnish with the pine nuts, extra dill, and lemon wedges.