Fill a large pot with lightly salted water and bring to a rolling boil; stir in rice noodles and return to a boil. Cook until tender yet firm to the bite, 3 to 5 minutes. Drain. Run cold water over noodles until cool enough to handle. Drain again and transfer to a large bowl. Add 2 tablespoons sesame oil and toss to coat.

Place tofu onto a plate and place another plate on top. Set a 3- to 5-pound weight on top. Press tofu for 20 to 30 minutes; drain and discard the accumulated liquid. Slice tofu into approximately ten 1/2-inch slices.

Heat 1 teaspoon grapeseed oil in a skillet over medium-high heat. Saute tofu slices until crisp on each side, flipping halfway through, 5 to 7 minutes total. Transfer to a cutting board and chop into cubes.

Combine remaining 2 tablespoons sesame oil, peanut butter, tamari, vinegar, agave, garlic, hot water, ginger, and red pepper flakes in the bowl of a food processor. Blend sauce until smooth.

Heat remaining 1 teaspoon grapeseed oil in a skillet over medium heat. Add red cabbage and green cabbage. Stir-fry for 2 minutes and remove from heat.

Add cooked tofu and stir-fried cabbage to the bowl with the noodles. Pour in 1/2 cup sauce and toss to coat. Add more sauce as desired; thin sauce with additional hot water 1 tablespoon at a time, if necessary.

Top with cucumber, carrot, and scallions. Drizzle additional sauce over entire dish as desired.