Sweet Potato Spears with Lemongrass Dip

• 3 sweet potatoes try to find evenly shaped ones, not too twisted or crooked
• Olive oil for brushing
• 1 tsp ground coriander
• 1 tsp coriander seeds
• 1 tsp yellow mustard seeds
• 3/4 tsp sea salt
• Fresh cracked pepper to taste
• 1 serrano or jalapeño pepper thinly sliced

for the Lemongrass Dip:

• 1 stalk lemongrass
• 3/4 cup Creme Fraiche Crema Mexicana, sour cream, or Greek yogurt
• Zest and juice of 1 lime
• 1 inch piece of ginger peeled
• 1/2 tsp sea salt