Prepare palm sugar: soak in cold water for 10 minutes. Drain, add 2 tsp water, and microwave for 2 minutes.
Add sweet potatoes, curry paste, vegetable stock, palm sugar, and thin soy sauce to slow cooker and stir.
Cook on high for 3 hours, until potatoes are tender.
Add tofu cubes (optionally fried, see below), coconut milk, and peanuts to slow cooker. Stir to combine and let heat through for 10 minutes.
OPTIONAL: Fried Tofu (+ ~20 minutes)
Press out the moisture using lots of paper towels and a plate.
Dice into 1 inch cubes.
Sautee in oil until all sides are lightly golden.
Drain on paper towels.
Notes
Palm sugar - 3 small rounds, about 45 g. Note that this is Thai palm sugar, not the granulated "coconut palm sugar" you can buy. Substitute light brown sugar or white sugar. Coconut palm sugar is too dark.