Heat canola oil in a large pot or wok over medium-high heat.
Add red curry paste and stir continuously until fragrant, about 1-2 minutes.
Pour in 3 tablespoons of coconut milk and cook briefly, stirring to combine with the curry paste.
Add water and bring to a simmer.
Add morning glory and cook for 1 minute until leaves begin to wilt.
Stir in remaining coconut milk, sugar, fish sauce, and tamarind paste.
Simmer for 2-3 minutes until all flavors are well combined and morning glory is tender.
Taste and adjust seasoning as needed.