Peel and cut the kohlrabi and potatoes to about 2 cm cubes.
Place in pot and cover with vegetable broth.
Cook for 15 minutes or until potatoes are tender.
Place a colander over a bowl and strain the vegetables while reserving about half of the broth. Set aside.
In the same pot, melt the margarine over medium-high heat and stir in the flour until it forms a thickened paste (roux).
Add the kohlrabi and potatoes back in and toss quickly to coat in roux.
Deglaze with the reserved broth until just covered and stir until the sauce has reached your desired consistency. Add more broth if needed.
Serve with some bread and / or veggie sausages!