This recipe is largely open-ended and designed so you can use whatever vegetables you want.
My rule of thumb for an expert crudité plate or bowl is to enhance each ingredient, but only slightly. For example, cauliflower and carrots benefit from a little heat-based tenderizing and caramelization with a little olive oil and salt to enhance their flavor. Notice we don't cook them to the point where they totally lose their crudeness aka rawness. Celery and rhubarb's texture and visual appeal can be improved by a soak in ice water. Onions, something some people despise raw, can be sweetened up by a soak with cucumbers in hot vinegared water. Fennel gets some mechanical tenderization by slicing it thinly on the mandolin and then has its sweetness put in check by some salt and lemon juice. See what we are doing here? We aren't cooking the life out of stuff, just manipulating it or changing its appearance. Tres Mysterio, non?
For the sand in this recipe, you will need maltodextrin and room temperature fat. To keep it vegan we used olive oil, but if you wanna get wild you could use bacon fat. Just whisk the fat and maltodextrin together adding enough maltodextrin to make a dry, sandy-feeling paste. Season it up as you'd like--we used cumin and salt. Then push it through a sieve to make your sand.
Finally, for full Mysterio fishbowl head effect, plate your veggies and sand up in a sanitized terrarium and pump it full of smoke with a hand-smoker or by adding a tiny bit of dry ice to a ramekin of water placed in the center of the terrarium.