This is a recipe that evolved as it went along rather than being planned from the start so I'll try to take you through the process.
Honestly, I'm surprised it took me as long as it did to come up with "ice cream" as the answer to the question "what am I going to do with the substandard coconut milk and hard to utilize coconut water in my refrigerator?". When it did, my first thought was to go with a simple sorbet: just add the water to the milk, mix in some sugar and dump it in the churn. But the coconut milk was really too mild, even punched up by the coconut water, and, after the punching up, a bit thin.
So I tossed idea of that pure raw drinking-coconut flavor and decided to cook the mixture down. I started with 2 1/4 cups of coconut milk, 1 1/2 cups coconut water and added 3/4 cup sugar. I have this idea in my head that if you boil coconut milk long enough it will caramelize and turn brown the way toasted coconut does. I know that seems improbable, but I remember doing it once even if I can't find the recipe or any mention of such a thing on-line and I remember plenty of recipes I've made where it didn't happen. Anyway, after 20 minutes of it not happening this time too, I figured that was enough and gave up. By that time I had cooked the mixture down to 3 cups even and it was a little thickened up. I added a couple Tablespoons of rum, a squeeze of lime and the zest from that lime wedge and gave it a taste. It was a nice cooked coconut flavor intense enough that I figured I could add a bit of dairy to help the texture without compromising the flavor unduly. So in went a half cup of half-and-half. Now it was tasting rather like coconut cream pie which got me thinking about mix-ins.
Bits of pie crust would, of course, be ideal, but I've been avoiding making pie crust for years and I'm not going to stop now. And supermarket pre-made crusts aren't likely to suit. On the other hand streusel topping's not a bad idea and I keep a little baggie of it pre-made in my pantry for desert emergencies. (Slice up a piece of fruit into an ovenproof bowl, add a bit of jam or juice, toss with a teaspoon of corn starch, cut the streusel mix with butter, sprinkle on top and bake at 350 until golden brown on top and bubbly underneath.) It's been there a while so I don't recall exactly what I put in it. Just flour, sugar, rolled oats and cinammon I think. No idea of ratios.
While the sherbet mix was in the churn, I baked maybe a half cup of streusel (cut with butter, of course) in my toaster oven. I know it looks burnt, but it's not. That burning smell is because I don't clean my crumb tray often enough. OK, maybe it's a little burnt but it's still in the I-can-pretend-I-did-that-on-purpose stage where the burnt flavor is interesting not nasty. I put it in the freezer to cool off while the churning finished and then stirred it in.
And here's the pretty-cool-looking final result:
Disappointingly, the bold coconut flavor of the warm mix and even right out of the churn has faded in the final ripened sherbet. It hasn't faded away entirely, but it's become subtle which moves the streusel a bit more to the forefront that I really wanted. It's not at all bad mind you, but doesn't wow the way I was hoping. The streusel is toasty, spicy and buttery as it should be, but without strong fruit to play against it comes on a bit strong. The texture is a bit crumbly, as sherbets tend to be, but it melts smoothly on the tongue and the streusel bits are still crisp and chewy the way they should be. Given how well it held up, I'm surprised streusel isn't a common ice cream mix in. It's certainly going to be complementing plenty of my fruit-based ice creams in the future.