Pat shrimp dry with a paper towel and set aside in a medium bowl. Whisk together remaining ingredients except for canola oil. Toss shrimp with paste.
Heat a large skillet over medium-high heat and add oil. Once hot add shrimp and cook in a single layer. Cook for about 2-2 1/2 minutes per side until the paste starts to caramelize and stick to the shrimp.
Remove shrimp to a serving plate and garnish with lime wedges and cilantro if desired. Serve immediately.
If the shrimp are too crowded in the pan they will not brown in the time it takes to cook them. They only take minutes to cook, so cook in two batches if you do not have a large enough skillet. Wipe out skillet between batches.
Slice green onions, separating the white and reserving the green for garnish. Whisk together coconut milk, curry paste, fish sauce, and brown sugar.
Heat oil in a medium sauté pan over medium heat. Add whites of green onion and garlic. Sauté for one minute and add shrimp in a single layer. Cook shrimp 2 minutes per side and remove from pan.
Add coconut milk mixture to the pan and bring to a full simmer. Add snow peas and stir to coat. Allow to simmer uncovered about 4 minutes over medium/high heat. Stir once or twice until snow peas are just tender and the sauce has reduced to a syrupy consistency.
Toss shrimp back into the pan and stir to coat with sauce and warm throughout for about 1 minute. Season lightly with salt.
Serve immediately over rice and garnish with reserved sliced green onions, fresh cilantro and a squeeze of fresh lime juice.