Fry up tempeh until crisp. Set aside to drain off excess oil. Pour out most oil from pan, leave just enough to stir fry onions. Fry onions till translucent, roughly 1-2 minutes.
Add in the carrots and garlic and continue to cook for 5 minutes on medium heat. (You may want to put a cover on the pan to let them steam at the same time.)
As this is going on, mix the 2 tablespoons of soy sauce with the flour, get out all lumps.
After the five minutes, add the paste (of soy and flour). As a hint, push all the veggies out of the way, so that it can boil by itself. Let the paste boil for a minute so that the flour cooks and the chalky taste of flour goes away. Add the orange juice and mix everything together.
Mix in chili garlic sauce and pineapple chunks. Let this reduce down. Test to see if sweet enough as different orange juices are sweeter than others. If not sweet enough add some vegan sugar. Add in the tempeh and green onions.
Serve over rice.