Wash the spinach leaves well. Grind the leaves to a fine paste, using 1/4 cup drinking water and strain to get fresh spinach juice. Peel, wash and grate the beetroot. Grind it to a paste and strain to get beetroot juice.
In a mixing bowl, add the Sathumaavu, cumin powder, crushed black pepper, 2 tbsp oil, salt and baking powder. Mix everything well to get a crumbly mixture. Divide the mixture equally into two bowls and keep aside.
Use the beetroot juice to one half of the sathumaavu mix and knead it to form dough. To the other half of the sathumaa, add the spinach juice and knead. Keep the dough covered for 10 minutes. Knead each dough portion again for a minute.
Roll out each portion of dough separately with a rolling pin till its thin enough for crackers. Using a round lid or small cookie cutter, cut the rolled dough into crackers. Use a fork to make patterns on the crackers and place them onto a greased or lined baking tray.
Bake the crackers at 180 degree Celsius for 7-8 minutes until they are crisp. You can serve them together or individually with a dip.