Place a pasta pot filled 2/3 full with hot salted water on the stove to boil.
Rinse, peel and shred your carrot in a food processor or using a grater. Rinse the green onions and trim off the root ends and any wilted green parts. Use scissors or a knife to cut the onions into small pieces. If using a bell pepper, rinse it, cut it in half and remove the seeds and membranes. Dice the peppers. Set aside all of your veggies, as they will be used raw in this dish.
When the water is boiling, add your fettuccine to the pot and give it a stir. Prepare your sauce while you occasionally stir the pasta.
In a food processor or blender, add all of the sauce ingredients. Process or blend until it's smooth.
Reserve a ladle of cooking water from the pasta pot and set it aside in a bowl. Cook the pasta until it is al dente, tasting it three minutes before the time listed on the package to see if it is done. When it is cooked, drain the pasta in a colander in the sink.
Transfer the pasta back to your pot and stir in the butter and reserved water. Stir in your veggies, reserving some for garnishing each serving, if you wish.
To serve, plate the fettuccine and veggies and stir in some peanut-sunflower sauce. Garnish with reserved veggies and onions, if you wish.
Store leftover pasta and sauce separately in the refrigerator for up to four days.