Wash the leeks thoroughly, then trim and thinly slice them. Peel and finely chop the garlic.

Zest the lemon, then squeeze its juice into a small bowl.

Melt the 25 g vegan butter in a large frying pan over medium heat. Add the chopped garlic and chili flakes.

Sauté the garlic and chili flakes until fragrant, stirring often. Add all sliced leeks to the pan.

Stir-fry the leeks over medium heat for about 10 minutes. Cook until very soft and jammy.

Combine the light miso paste, tahini, lemon juice, lemon zest, white wine vinegar, agave syrup, and 75 ml water. Stir until smooth.

Pour the miso-tahini mixture into the frying pan. Stir it through the softened leeks until evenly combined.

Bring a large pot of water to a boil. Cook the dry pasta until al dente according to its package instructions.

Reserve 120 ml pasta water, then drain the cooked pasta. Add the pasta to the leek sauce.

Add the reserved pasta water and toss until the pasta is glossy and coated. Stir in cilantro, if using.