Dissolve the yeast in the warm water, add vinegar. Gradually add the flour mixed with the salt, the walnut kernels, roughly mashed with the ball of your hand, and the sunflower kernels, mix well with the dough hook and then work the dough through well.
Pour the mixture into 2 well-greased loaf tins and smooth the surface with a wet spatula. Possibly put a pattern with sunflower seeds on the surface. Cover the dough and let rise for about 30 minutes.
Bake in a preheated oven to 220 degrees for about 45 minutes. Of course, the baking time always depends on the oven in question.