Take collard leaves and cut or tear out the ribs. Discard the ribs. in two or three batches, pile collard leaves on top of each other, tightly roll them up lengthwise and cut into 1/4' slices.
In a large skillet, heat up oil over medium heat. Add onions and bell peppers when oil is sizzling, and cook until they just begin to soften, about 2 minutes. Raise the heat to medium-high and add half the collards, stirring to wilt them. When wilted, add the second half of the collard greens, stirring to combine.
Sprinkle the Stubb's Chicken Spice Rub over greens and pour in the water to help them steam, stirring frequently; cook for about 3-5 minutes. When water is almost gone, take the pan off the heat. Taste and season with vinegar, salt and pepper as needed. Serve warm.