Preheat oven to 375ºF.
Wash the potatoes and, if necessary, cut a section from the bottom so the potatoes can sit flat on the cutting board.
Place wooden chopsticks on either side of the potato and using a sharp knife, slice the potatoes approximately 1 centimeter thick without cutting all the way through. The chopsticks will help prevent this from happening, but you will need to be more careful on the ends as the chopsticks may not be high enough.
Gently fan open the potato and place in a baking dish. Repeat with the rest of the sweet potatoes.
Brush and drizzle 1 tablespoon of olive oil over the potatoes, making sure you brush between the potato slices. Season with 1/8 teaspoon salt, 1/8 teaspoon pepper and 1 teaspoon fresh thyme.
Bake until fork tender, but not mushy, about 1 hour.
While potatoes are baking, place a skillet over medium high heat and add 1 tablespoon of extra virgin olive oil.
When oil is hot, add onion slices. Sauté until onions soften and then reduce heat to low. Continue cooking and stirring onions until they brown and start to caramelize, approximately 30-45 minutes.
When onions are caramelized, stir in 1/3 cup raisins, 2 tablespoon pecans, 1/8 teaspoon salt and 1 teaspoon fresh thyme.
About 15 minutes before the potatoes are done cooking, sprinkle the onion-raisin mixture over the potatoes and resume cooking until potatoes are done.