These sandwiches have it all - sweet, savory, spicy, tangy, creamy, and crunch! You're going to melt when you sink your teeth into this.
Preheat oven to 425°F.
In a mortar and pestle, crush the mustard seeds and then add to a bowl with the rest of the spice mix.
Brush 1/2 teaspoons of oil on each beet and place in foil. Create a foil packet by placing all the beets in the foil and wrapping tightly to cover completely. Roast for 45 minutes for small beets or longer for larger beets (time may vary).
Open up foil carefully, as hot steam will be coming out. Beets should easily be punctured by a fork. If not, continue roasting in the foil packet.
Generously brush the liquid that has pooled in the foil packet over the beet skin to get it wet, then generously cover in the pastrami spice on outside of the beet so it’s covered evenly. Keep them spaced apart on the foil, but you don’t need to wrap them again. Roast for another 15 minutes so the moisture evaporates and the paste sticks.
Remove the beets from the oven and slice very thinly.
Spread 4 pieces of bread with vegan butter on the outside and thousand island dressing on the inside. Top with vegan cheese and 1 sliced beet per sandwich. Then top with sauerkraut, more cheese and top with a piece of bread with thousand island on the inside and more butter on the outside.