Thinly slice the capsicums. Crush or finely chop the garlic. Tear the kale leaves into small pieces, discarding the stems.
Step 2 — Make miso stock
Put the miso paste, half the tomato paste*, and 125ml (½ cup) boiling water in a heatproof jug and stir to dissolve. Bring a large saucepan of salted water to the boil for the pasta.
Step 3 — Make capsicum sauce
Heat 2 tsp olive oil in a medium saucepan over high heat. Cook the capsicum, stirring occasionally, 4-5 mins until charred. Reduce heat to medium. Add the garlic and ½ tsp chilli flakes* and cook, stirring, for 1 min or until fragrant. Add the miso stock and half the tomatoes*. Reduce the heat to low and cook, covered, for 10 mins or until the sauce is reduced.
Step 4 — Cook pasta and kale
FRESH FETTUCCINE OPTION While the sauce is cooking, add the pasta to the pan of boiling water and cook, stirring to separate the strands, for 2 mins. Add the kale and cook for a further 2 mins or until the pasta is al dente. Reserve 60ml (¼ cup) cooking water, then drain the pasta and kale.
Step 5 — Make lemon salsa
Meanwhile, very finely chop one-quarter of the lemon*, discarding any seeds. (Both lemon peel and flesh is used; the peel adds a distinctive texture and tartness, but if you're not a fan, simply use lemon zest and juice.) Finely chop the parsley leaves, discarding stems. Combine chopped lemon, parsley and 1½ tbs extra virgin olive oil in a bowl and season with salt and pepper.
Step 6 — Toss pasta and sauce
Using a stick blender, blend the capsicum sauce until almost smooth (take care as the mixture may spit). Taste, then season with salt and pepper. Add the pasta, kale and reserved cooking water to the sauce and cook, tossing, for 1-2 mins until glossy. Finely grate the parmesan. Divide pasta among bowls. Scatter over the parmesan and serve with the lemon salsa.