The base of the soil was made from Dutch Pumpernikel bread. It's perfectly dark and dense for the job. Black tahini added a touch of richness and moisture to it, but for a gluten-free and Paleo version I think a mixture of cooked buckwheat and black tahini would work just as well. As for the veggies - well, the choice is yours. I find that lightly blanched beans make good "snakes", steamed cauliflower and roasted carrots provide sweetness and soft texture against crunchy cucumbers and pops of tomato flavour.