Grilled Argentine Tri-Tip Sandwich with Cherry-Strawberry Chutney

Ingredients

• 1 piece of Argentine tri-tip
• 1 tbsp olive oil
• Salt and black pepper, to taste
• 1 large onion, thinly sliced
• 1 cup fresh cherries, pitted and halved
• 1 cup fresh strawberries, hulled and chopped
• ¼ cup dark brown sugar (muscovado)
• 2 tbsp balsamic vinegar
• Juice of 1 lime
• ¼ cup water