Preheat oven to 400°C (205°C). Line a large sheet pan with parchment paper. Set aside. On a smaller sheet pan, add the almonds in a single layer. Toast the nuts until lightly browned and fragrant. Sliced almonds will take about 5-6 minutes. Whole almonds about 8-10 minutes. If using whole almonds, allow to cool, then roughly chop. Set aside.
Slice sweet potatoes into wedges, cutting them all roughly the same size. In a large bowl, combine the wedges with the olive oil, spices, salt and pepper. Toss to coat well. Place wedges, cut side down, on prepared sheet pan. Bake for 20 minutes. Flip each sweet potato wedge, using a spatula, and bake for 20 minutes more or until wedges are nicely browned.
While wedges are baking, make romesco sauce. In a small food processor, add the garlic and parsley. Pulse to roughly chop. Add the roasted pepper, almonds, tomato paste, vinegar, paprika, cayenne, salt and pepper. Add olive oil, starting with 2 tablespoons. Pulse to coarsely blend everything. Taste and check texture. If a more smooth texture is desired, blend a bit more. Add more olive oil (a tablespoon at a time) to loosen, if desired. Add more salt, if needed.
Serve hot wedges with romesco sauce. Garnish with extra parsley or cilantro leaves, if desired.