Recipe here: https://twitter.com/IKEAUK/status/1252269467515617280

What should we use to replace the breadcrumbs in the meatballs? I suppose port rinds is possible. Coconut flour might work and I actually have some. I'll try that.

Meanwhile, the sauce has wheat flour which you might not really need at all, but if you do want to thicken it you could very carefully use egg yolk by stirring a bit of the sauce into the egg yolk and making a custard like sauce. Or you could use mustard flour, which is basically powdered mustard, in place of the mustard.