Bring a large pot of salted water to a boil. Add the noodles and cook them according to the package directions, until al dente. Drain them into a colander when they're done.
Make the sauce while the noodles cook. First whisk together only the kecap manis, lime juice, and sambal oelek. You will add the other sauce ingredients later. Set the mixture aside for now.
Place a large skillet over medium heat, then add 1 tablespoon of the oil. Swirl it around to coat the bottom of the skillet, then let the oil heat up for a minute.
Cut the tempeh into about 18 thin strips (cut parallel to the short side), while the oil heats up.
Add the tempeh strips to the skillet in a single layer. Cook them for about 4 minutes on each side, until golden brown and crispy. Carefully pour only about half of the sauce over the tempeh strips. Cook them for about 2 minutes longer, flipping once, until the sauce thickens and caramelizes on the tempeh strips. Remove the tempeh from the skillet and transfer it to a plate.
Whisk the peanut butter and soy sauce into the remaining sauce, then thin the mixture with 2 tablespoons of water, or as much as you need to make it easily pourable.
Add the remaining tablespoon of oil to the skillet and raise the heat to medium-high. Give the oil a minute to heat up, then add the shallots. Cook the shallots for about 4 minutes, stirring frequently, until they soften and begin to crisp around the edges. Remove the shallots from the skillet and transfer them to the plate with the tempeh.
Add a dash more oil to the skillet if it seems dry, then add the cabbage and bell pepper. Cook the veggies for about 2 minutes, stirring constantly, until they brighten in color and become tender-crisp.
Push the cabbage and pepper to the sides of the skillet, then add the garlic. Sauté the garlic for about 30 seconds, stirring constantly, until it becomes very fragrant.
Add the cooked noodles and shallots to the skillet, then carefully pour the sauce over them. Cook the noodles and veggies in the sauce for 1 to 2 minutes, until everything is heated and the sauce clings to the noodles.
Remove the skillet from heat. Divide the noodles among 3 bowls, then top the noodles with the tempeh, cucumber, and cherry tomatoes. Sprinkle each bowl with scallions and cilantro, then serve immediately.