Cut tempeh lengthwise into 1/4" slices. Then, cut each slice in thirds. Set aside.
Cut broccoli into small florets. Thinly slice bell peppers lengthwise. Cut zucchini in half lengthwise, then slice into 1/4" half-moons. Set aside all prepped veggies.
Mix miso-peanut sauce ingredients together in a small bowl. Slowly add 1 Tbsp of warm water at a time, whisking with a fork, until desired consistency is reached (I used 8 Tbsps of water). Adjust to taste, mix until smooth, and set aside.
Heat a large skillet, wok, or frying pan over high heat and add avocado oil. Bring a large pot of water to a boil.
Once hot, add broccoli florets to skillet, cooking for ~5 minutes. Then, add bell peppers, zucchini, and tempeh slices. Continue to cook for ~10 minutes, mixing around well.
Once water has boiled, add brown rice noodles. Cook according to package directions. Be careful not to leave the noodles in too long - they can over cook quickly! Drain and rinse noodles once finished.
Once veggie-tempeh mix is well cooked and slightly browned, remove from heat. Add noodles to the skillet and pour over miso-peanut sauce. Mix together well, until ingredients are coated in the sauce.
Serve + enjoy hot. Option to top with a sprinkle of sesame seeds, or red chilli flakes for a bit of spice!