Shake, don't stir. Shaking aerates the coconut milk and thins the sweetness just enough. The base keeps 5-7 days in the fridge in a sealed jar; stir before using because the purée settles. Do not freeze the finished drink - the coconut milk splits. Instead, freeze the base in an ice cube tray: two cubes, a splash of coconut milk, a little water, shake. It is the 30-second emergency version. If the base tastes flat by day four, a squeeze of lime brings it back. Use carton coconut milk, not canned. If canned is all you have, thin it 2:1 with water and add a pinch of sugar. For the oat milk version, swap the coconut milk 1:1; it is creamier and more latte-like.