Bring a medium saucepan of salted water to the boil for the spaghetti. Discard the husk and silks from the corn, then slice the kernels from the cob.
Step 2 — Prep tomato mixture
Coarsely chop the tomatoes. Juice half the lemon*. Combine the tomato and 3 tsp lemon juice* in a bowl and season with salt and pepper.
Step 3 — Cook spaghetti and corn
Cook three-quarters of the spaghetti* (see cooking tip) in the pan of boiling water for 7 mins. Add the corn, return to the boil and cook, stirring occasionally, for a further 5 mins or until the spaghetti is al dente. Reserve 2 tbs cooking water, then drain the spaghetti and corn. Return to the pan.
Step 4 — Slice haloumi
Meanwhile, slice the haloumi.
Step 5 — Cook haloumi
Heat 2 tsp olive oil in a medium frypan over medium-high heat. Cook the haloumi for 2 mins each side or until golden. Remove from the heat.
Step 6 — Get ready to serve
Add the pesto and tomato mixture to the spaghetti and corn and return to medium-low heat. Gradually add the reserved cooking water, tossing constantly, for 1 min or until the spaghetti is coated. Taste, then season with salt and pepper. Divide the spaghetti and haloumi among bowls to serve.