Place a frying pan on a medium heat for a few mins. When warm, add the pumpkin seeds with a pinch of salt and toast for 3-4 mins, shaking the pan, till they start to pop and darken slightly. Tip into a small food processor bowl (see our tip below if you don’t have food processor).
Zest the lemon into the food processor and squeeze in the juice from 1 half. Peel and grate the garlic clove into the bowl. Roughly tear half the basil leaves and add those too. Drizzle in 2 tbsp olive oil and 2 tbsp cold water. Add salt and pepper.
Pulse a few times till you have a chunky paste. Taste add a little more salt, pepper or lemon juice to taste. Set to one side.
Slice the large vine tomatoes into 6-8 wedges each. Halve the heirloom and cherry vine tomatoes. Pop them into a large bowl. Drain and rinse the haricot beans and add to the bowl with the tomatoes.
Pour in the pesto dressing. Tear in the remaining basil leaves and gently toss everything together. Taste and adjust the seasoning as necessary, adding more lemon juice to taste. Arrange on 2 plates and serve straight away.