Cut the cherry tomatoes in half and place on one half of a lined baking tray. On the other half of the baking tray, evenly spread the sunflower seed kernels. Cook under a grill for 3 – 5 minutes, or until they seeds become golden and tomatoes are just tender and start to slightly blister. Set aside. Scoop out the flesh of the avocado and dice, add to a bowl along with spinach leaves. Drizzle with balsamic dressing to taste, gently toss to combine. Serve alongside slices of toasted rye bread. FOR DRESSING: Drop the garlic clove in a food processor while the machine is running on high speed. Scrape down sides of bowl. Add olive oil, vinegar, salt, sugar and red pepper flakes. Blitz on high speed for 30 seconds. Can be prepared 6 hours ahead. Transfer to small bowl. Cover and let stand at room temperature. Re-whisk before using if necessary.