Heat olive oil in a large pot over medium heat.
Add the diced onion and cook for 5-7 minutes until softened.
Stir in the minced garlic, grated ginger, yellow curry powder, turmeric, and cumin.
Cook for another 1-2 minutes, stirring constantly, until fragrant.
Add the cubed sweet potatoes to the pot and stir to coat in the spices.
Pour in the coconut milk and vegetable broth. Bring to a simmer.
Let it cook for about 20-25 minutes, or until the sweet potatoes are tender.
Once the sweet potatoes are cooked through, stir in the soy sauce, lime juice, salt, and pepper.
Taste and adjust seasoning as needed.
Serve the creamy Thai sweet potato curry over steamed rice, garnished with fresh cilantro and lime wedges.