For the lentil soup, preheat oven to 200 °C convection broil function. Cut smoked tofu into small cubes and thoroughly toss with potato starch in a bowl until all cubes are coated with the starch.
Place the tofu cubes on a sheet of baking paper and grill 2x for 15 minutes. At the halfway point, turn all the cubes over once. They are done when they are brown and crispy all over.
Wash lentils thoroughly in a colander until water remains clear. Chop onions and garlic and sauté in sesame oil until translucent.
Pour in soup, add lentils, ginger and lemon juice and simmer for 10-15 minutes until lentils are soft but not broken down.
Season soup with lemon juice and salt and serve with tofu croutons.