This is a stir-fry recipe I devised and now love. Be sure to press tofu to get rid of its water by pressing it, wrapped in paper towels or a clean towel, for 30 minutes to a few hours under heavy cookbooks.
In a bowl, prepare sauce: combine heated broth and cornstarch, stirring to dissolve. Add vinegar, soy sauce, brown sugar, and red pepper flakes (to taste). Set aside.
In another bowl, toss eggplant in a few shakes of salt. Let eggplant cubes sit in salt for 20-30 minutes, then rinse with water and pat dry. Doing this eliminates the slightly bitter taste eggplant sometimes has. Set prepared eggplant cubes aside.
Heat oil in a large skillet or wok on stovetop.
Add minced garlic and diced onion and fry until onion becomes golden or translucent.
Add broccoli and stir-fry about 2 minutes, adding more oil or broth if veggies begin to stick to pan.
Add cubed tofu and continue to cook 1-2 minutes; then add cubed eggplant and keep cooking 4-5 minutes, stirring to keep from sticking to the pan bottom.
Finally, turn heat down to medium or a simmer. Stir the sauce you've prepared, and then pour it into the pan. Continue to cook until the sauce thickens nicely.