Preheat the oven to 400°F/205°C.
To a sheet pan, add the sweet potato. Drizzle with olive oil, and season with salt and pepper. Toss until the seasonings are evenly distributed and spread in an even layer. Roast for 20-30 minutes or until fork tender (start checking at 20 minutes). When ready, remove from the oven and allow to cool.
Meanwhile, make the dressing, in a bowl or a small jar combine the olive oil with lemon juice, maple syrup, Dijon mustard, garlic, salt and pepper. Whisk until well combined, or if using a jar then shake until combined.
Assemble the salad. In a large bowl combine the salad mix with cranberries, cooled sweet potato chunks, and avocado. Toss to combine.
Dress the salad with ¾ of the dressing and toss again (taste the salad, and tweak the seasonings if needed, more salt or pepper or lemon juice, etc). Transfer to a serving bowl or plate, and top with crumbled goat cheese. Drizzle with the remaining dressing before serving.