Peel and dice avocado, mango, and red onion. Mince jalapeno and cilantro.
Combine avocado, mango, jalapeno, onions, cilantro, 2 teaspoons olive oil, lime juice, and salt to taste.
Pat tuna steaks dry, season with salt and pepper. Heat 2 tablespoons vegetable oil in a large saute pan over medium-high heat until lightly smoking (needs to be hot). Add tuna and sear 2-3 minutes on each side for medium-rare. Serve with salsa.
To prepare yellow squash, cut into half moon shapes and heat up 1 tablespoon vegetable oil in a skillet over medium-high until hot. Carefully add squash and do not stir for about 1 minute. Stir and continue to saute 3 minutes, or until squash is browned and crisp-tender. Season with salt and pepper.