Rinse and drain the rice three times. Add 1 C. (250 ml) filtered water to the rice in a saucepan, put on the lid, and bring to a boil over medium-high heat (about 5 minutes). Turn down to simmer and cook for 35 minutes, leaving the lid on. Turn off the heat and let sit for 10 minutes. Mash the rice with a potato masher or your hands to get it really sticky.

Preheat broiler to high.

Cut each bread slice into a 3 inch (6-8 cm) circle using a round cutter. Lightly coat bread rounds and scraps with cooking spray. Arrange all pieces in a single layer on a baking sheet. Broil 2 minutes on each side or until lightly toasted. Cool on a wire rack. When cool, pulse the scraps in the food processor to create bread crumbs, then use about 1/2 C. (or as much as are needed) to get the right texture. Store the rest in a tightly lidded container for another use.

Reduce oven temperature to 400F/200C/gas mark 6. Place a baking sheet covered in parchment paper in oven to preheat.

Put the ground flax seeds and 4 tbsp 60 ml filtered water together in a small bowl and set aside.

Saute the walnuts and the minced shallots in about 1 T. (15 ml) olive oil until golden brown.

Combine rice, walnuts, shallots, beets, bread crumbs, parsley, salt and pepper in a medium bowl. Whisk mustard into the flax mixture. Add mustard mixture to rice mixture; stir until well blended.

Pack rice mixture into a round cookie cutter, setting each on waxed paper. Remove mold. Form 8 patties.

Heat a large skillet over medium-high heat. Add a drizzle of olive oil to pan; swirl to coat. Carefully add 4 patties to pan; cook 2 minutes. Transfer patties to preheated baking sheet, turning patties over and arranging in a single layer.

Repeat procedure with remaining oil and the last 4 patties.

Place pan in oven; bake patties for 9 minutes. If desired, top each patty with 1 vegan cheese slice; bake an additional 1 minute or until cheese is soft and patties are set.

Place 8 toasted bread rounds on a flat surface; top each round with 1 patty. Divide watercress or arugula evenly among sliders; top with the remaining toasted bread rounds.