Fill and boil your kettle. Tip the lentils into a small pan and add a pinch of salt. Pour in 200ml boiling water and set the pan on a high heat. Bring to the boil, cover with a lid and turn the heat down to a low simmer. Cook the lentils for 20-25 mins, till tender. If the pan dried out too quickly, turn the heat down and add a splash more water. When cooked, drain the lentils and rinse them with cold water.
While the lentils cook, set your grill to medium-high. Slice the tomatoes into 6-8 wedges each and pop them on a large baking tray. Peel the red onion and slice it into 6-8 wedges to match. Trim the bases off the lettuces and cut them into quarter wedges. Add the onion and lettuce wedges to the baking tray, spreading them into an even layer. Drizzle the veg with 1 tbsp olive oil and season with a pinch of salt and pepper.
Slide the veg under the grill for 3-4 mins, till charred at the edges, then turn over and grill for another 3-4 mins.
Peel and grate the garlic into a bowl. Roughly chop the mint leaves and add them to the garlic. Add 1 tbsp each olive oil and cider vinegar and a pinch of salt and pepper. Whisk into a dressing.
Shake the cooked lentils dry and tip them into a mixing bowl. Add the grilled veg and drizzle over the garlic and mint dressing. Gently toss to mix. Divide the salad between 2 warm plates and serve topped with the goat's cheese.