Preheat the oven and the pan. Set the oven to 400F. Put your baking sheet into the oven while it preheats so the pan gets hot, which keeps the sweet potato from sticking.

Season the sweet potato. While the oven heats, peel and cube the sweet potato. Put the cubes in a shallow bowl and season with the avocado oil, all spice, sea salt, and pepper, then work the seasoning in with your hands until every surface looks evenly coated.

Roast. Add the seasoned cubes to the hot baking sheet and return it to the oven for 20 to 25 minutes, stirring midway so the cubes brown on more than one side.

Build the salad bowl. While that roasts, add the lettuce, finely chopped onion, finely chopped dill, coarsely chopped walnuts, dried cranberries, and crumbled feta cheese to a large salad bowl.

Shake the dressing. Add the Dijon mustard, apple cider vinegar, maple syrup, and olive oil to a sealable jar and shake until well combined. It should look uniformly cloudy rather than showing separate layers.

Dice the avocado. About 5 minutes before the sweet potato will be done roasting, cut the 1/4 avocado into dice and add it to the salad as well. Leaving it this late keeps it green and intact.

Combine and toss. Add the roasted sweet potato to the salad bowl, drizzle the dressing over everything, and give it a good toss.