Add 10 cups water and 2 tsp salt to a large pot (use same for 4 ppl). Cover and bring to a boil over high heat. Before starting, wash and dry all produce. Core, then cut pepper into ¼-inch slices. Thinly slice green onion.Peel, then mince or grate garlic.
Heat a large non-stick pan over medium-high heat. When hot, ½ tbsp oil (dbl for 4 ppl), then beef and pork mix, half the garlic and 1 tbsp oyster sauce (dbl for 4 ppl). Cook, breaking up meat into smaller pieces, until no pink remains, 4-5 min.** Remove from heat. Season with salt and pepper, to taste. Transfer beef and pork mix to a plate, then cover to keep warm.Carefully wipe the pan clean.
Reheat the same pan over medium-high. When hot, add ½ tbsp oil (dbl for 4 ppl), then peppers and remaining garlic. Cook, stirring often, until peppers are tender-crisp, 3-4 min.
Meanwhile, add chow mein noodles to the boiling water. Cook uncovered, until tender, 1-2 min. Drain noodles, then rinse under warm water. Return noodles to the same pot, off heat. Add ½ tbsp oil (dbl for 4 ppl), then gently toss to coat. Using a pair of scissors, make a few cuts to chop up noodles.Set aside.
Add ginger sauce, remaining oyster sauce and ½ cup water (dbl for 4 ppl) to a small bowl. Season with pepper, then whisk to combine. Add coleslaw cabbage mix and prepared sauce to the pan, then bring to a simmer. Cook, stirring occasionally, until sauce thickens slightly and coleslaw cabbage mix is tender-crisp, 1-2 min.Remove from heat.
Add veggies, sauce and beef and pork mix to the pot with noodles. Season with salt and pepper, then toss to combine.Divide noodles and any sauce from the pot between bowls.Sprinkle green onions over top.