Drizzle the kohlrabi slices in a little lemon or vinegar to prevent it from going brown. Just before making, blanch the kohlrabi slightly until tender.: The initial lemon or vinegar touch introduces a faint citrus scent and slows oxidation, so the pale flesh stays visually inviting. As you drizzle, you should notice a faint bright smell from the citrus, and the slices will slightly shine, which helps them layer neatly. This acid also starts to tenderize the surface, making later blanching more even. One mistake people make is overdoing the acid, which can make the slices limp; use just a little to preserve crispness.
Make the avocado filling by mixing all the ingredients together until well combined and season to taste.: When blanching, steam or simmer water produces a gentle vegetal steam aroma and softens the kohlrabi just enough to be pliable without losing structure. You want a tender bite, not mushy, so monitor closely and test a slice for slight resistance. Cooling the slices in an ice bath stops cooking and preserves the pale color. A common error is leaving them in hot water too long, which yields soggy, fragile rounds that will fall apart during assembly.
Make the pea purée by blitzing all the ingredients in a blender adding as much oil as you need to make it a runny consistency.: As you mash and combine, you will notice a creamy, buttery aroma from the avocado and a tangy lift from the cream cheese and lemon . The texture should be smooth but with tiny herb flecks from the coriander . Season slowly with salt and pepper , tasting between additions, because the delicate balance can change quickly. If the filling is too loose, chilling it briefly firms it up; if it's grainy, it usually means the avocado was slightly underripe.
Assemble by layering slices of kohlrabi, fill with the avocado filling, top with another kohlrabi slice and lightly seal the edges with a fork.: When you blend the peas and garlic , expect a sweet, green aroma and a smooth, bright green color. Add olive oil in a slow stream while the blender runs to emulsify into a silky sauce; this gives a glossy sheen and a luxurious mouthfeel. Taste for seasoning, adding salt and a squeeze of lemon juice to brighten. A frequent pitfall is underblending, which leaves a grainy texture; blend until completely smooth and adjust oil for desired looseness.
Once you have used up all the ravioli, drizzle over the pea purée and garnish with the baby spinach, hazelnuts and edible flowers. Drizzle a good EVOO on top and finish with a grating with lemon zest.: During assembly you will appreciate the contrast of cool, creamy filling against the crisp, slightly chilled kohlrabi. Each little ravioli should sit flat and look neat; sealing with a fork compresses the edges so the filling stays inside. Work on a cool surface to keep the filling from softening too fast. One error to avoid is using too much filling, which prevents a good seal and leads to leaks when drizzled with purée.
Once you have used up all the ravioli, drizzle over the pea purée and garnish with the baby spinach, hazelnuts and edible flowers: As you plate, spoon the pea purée in a thin ribbon or dot pattern so each ravioli gets a bright lift. Scatter the baby spinach and chopped hazelnuts for texture and visual depth, and tuck a few edible flowers on top for color. Finish with a drizzle of high quality olive oil and a light grating of lemon zest to release citrus oils. Watch for overgarnishing, which can hide the delicate ravioli; aim for balance so each element is perceptible.